Bookmarks   　
nPr and nCr    
Random Number    
SD Calculator    
Sample Size    
Percent Error    
Density    
Molarity    
Molar Mass    
Ohm's Law    
Watts to Amps    
Voltage Drop    
Long Division    
Mixed Numbers    
Rounding    
Nth Root    
Exponents    
Half-Life    
Polar Form    
De Moivre    
3D Distance    
Point to Line    
Cross Product    
Determinant    
Sin Cos Tan    
Triangle Area    
Scale Factor    
Sector Area    
Ellipse Area    
Cube Volume    
Box Volume    
Sphere Volume    
Cone Volume    
Pipe Volume    
Time Duration    
Time Card    
Present Value    
Future Value    
Churn Rate    
A/B Test Calc    
SEO Traffic    
Ideal Weight    
Body Fat Calculator    
Lean Body Mass    
Fat Intake    
Child Height    
Golf Handicap    
Heat Index    
Wind Chill    
Dew Point    
Download Time    
kWh to Cost    
AC Size (BTU)    
Heating Costs    
LED Savings    
Trip Gas Cost    
Tire Size    
Solar Output    
Solar Payback    
Battery Size    
Wall Area    
Gravel Needed    
Mortar Mix    
Slope Grade    
Curtain Size    
Soil Needed    
Sod Needed    
Ramp Length    
Blind Size    
Drain Slope    
Board Feet    
Heat Loss    
Furniture Fit    
Moving Boxes    
Plywood Cuts    
Shelf Sag    
   Add
Probability and random number calculators
Independent Events
Independent Events
Two Events Solver
Two Events Solver
Repeated Trials
Repeated Trials
Bayes' Theorem
Bayes' Theorem
Expected Value
Expected Value
Binomial Distribution
Binomial Distribution
nPr and nCr
nPr and nCr
Circular Permutation
Circular Permutation
With Repetition
With Repetition
Random Number
Random Number
Averages and statistics calculators
Average Calculator
Average Calculator
Mean Median Mode
Mean Median Mode
SD Calculator
SD Calculator
Quartiles & IQR
Quartiles & IQR
Frequency Table
Frequency Table
Correlation (r)
Correlation (r)
Normal Probability
Normal Probability
Z-Score Calculator
Z-Score Calculator
Confidence Interval
Confidence Interval
Sample Size
Sample Size
Mark & Recapture
Mark & Recapture
P-Value Calculator
P-Value Calculator
Percentage and ratio calculators
Percentage Calc
Percentage Calc
Percent Change
Percent Change
Percent Difference
Percent Difference
Percent Error
Percent Error
Ratio Calculator
Ratio Calculator
Discount Calculator
Discount Calculator
Sales Tax Calculator
Sales Tax Calculator
Margin Calculator
Margin Calculator
Speed calculators
Speed Calculator
Speed Calculator
Density and concentration calculators
Density
Density
Molarity
Molarity
Molar Mass
Molar Mass
Physics and electricity calculators
Ohm's Law
Ohm's Law
Watts to Amps
Watts to Amps
Resistor Colors
Resistor Colors
Voltage Drop
Voltage Drop
Unit conversion calculators
Weight Converter
Weight Converter
Shoe Size Converter
Shoe Size Converter
Integer and signed number calculators
Long Division
Long Division
LCM Calculator
LCM Calculator
GCF Calculator
GCF Calculator
Integer Calculator
Integer Calculator
Prime Factorization
Prime Factorization
Diophantine Solver
Diophantine Solver
Modulo Calculator
Modulo Calculator
Factor Calculator
Factor Calculator
Roman Numerals
Roman Numerals
Fraction, decimal and rounding calculators
Fraction Calculator
Fraction Calculator
Mixed Numbers
Mixed Numbers
Simplify Fractions
Simplify Fractions
Fraction to Decimal
Fraction to Decimal
Decimal to Fraction
Decimal to Fraction
Rounding
Rounding
Equation and inequality calculators
Linear Equation
Linear Equation
Linear Systems
Linear Systems
Quadratic Formula
Quadratic Formula
Absolute Value
Absolute Value
Quadratic Inequality
Quadratic Inequality
Polynomial calculators
Binomial Theorem
Binomial Theorem
Square root and nth root calculators
Simplify Radicals
Simplify Radicals
Nth Root
Nth Root
Exponent and logarithm calculators
Exponents
Exponents
Log Calculator
Log Calculator
Number of Digits
Number of Digits
Scientific Notation
Scientific Notation
Sci. Notation Math
Sci. Notation Math
Half-Life
Half-Life
Complex number calculators
Complex Numbers
Complex Numbers
Polar Form
Polar Form
De Moivre
De Moivre
Function and graph calculators
Slope Calculator
Slope Calculator
Linear Function
Linear Function
Direct & Inverse Variation
Direct & Inverse Variation
y = ax² Calculator
y = ax² Calculator
Distance Formula
Distance Formula
3D Distance
3D Distance
Section Formula
Section Formula
Point to Line
Point to Line
Lat/Long Distance
Lat/Long Distance
Complete the Square
Complete the Square
Circle Equation
Circle Equation
Conic Sections
Conic Sections
Polar Coordinates
Polar Coordinates
Sequence calculators
Arithmetic Sequence
Arithmetic Sequence
Geometric Sequence
Geometric Sequence
Fibonacci Sequence
Fibonacci Sequence
Recurrence Relation
Recurrence Relation
Vector calculators
Vector Calculator
Vector Calculator
Cross Product
Cross Product
Matrix calculators
Matrix Calculator
Matrix Calculator
Determinant
Determinant
Inverse Matrix
Inverse Matrix
Plane geometry calculators
Sin Cos Tan
Sin Cos Tan
Degrees ⇔ Radians
Degrees ⇔ Radians
a sin θ + b cos θ
a sin θ + b cos θ
Triangle Solver
Triangle Solver
Triangle Area
Triangle Area
Right Triangle
Right Triangle
Pythagorean Theorem
Pythagorean Theorem
Polygon Angles
Polygon Angles
Scale Factor
Scale Factor
Parallel Lines
Parallel Lines
Rectangle Area
Rectangle Area
Parallelogram Area
Parallelogram Area
Trapezoid Area
Trapezoid Area
Circle Calculator
Circle Calculator
Sector Area
Sector Area
Inscribed Angle
Inscribed Angle
Ellipse Area
Ellipse Area
Solid geometry calculators
Cube Volume
Cube Volume
Cube Surface Area
Cube Surface Area
Box Volume
Box Volume
Box Surface Area
Box Surface Area
Cylinder Volume
Cylinder Volume
Cylinder Surface
Cylinder Surface
Sphere Volume
Sphere Volume
Sphere Surface
Sphere Surface
Spherical Cap Volume
Spherical Cap Volume
Cap Surface Area
Cap Surface Area
Ellipsoid Volume
Ellipsoid Volume
Ellipsoid Surface
Ellipsoid Surface
Pyramid Volume
Pyramid Volume
Pyramid Surface
Pyramid Surface
Cone Volume
Cone Volume
Cone Surface Area
Cone Surface Area
Frustum Volume
Frustum Volume
Frustum Surface Area
Frustum Surface Area
Pipe Volume
Pipe Volume
Capsule Volume
Capsule Volume
Capsule Surface Area
Capsule Surface Area
Date and time calculators
Age Calculator
Age Calculator
Days Between Dates
Days Between Dates
Date Calculator
Date Calculator
Hours From Now
Hours From Now
Day of the Week
Day of the Week
Time Calculator
Time Calculator
Time Zone Converter
Time Zone Converter
Hours Calculator
Hours Calculator
Time Duration
Time Duration
Time Card
Time Card
Finance and economics calculators
Compound Interest
Compound Interest
Simple Interest
Simple Interest
Interest Calculator
Interest Calculator
TVM Calculator
TVM Calculator
Present Value
Present Value
Future Value
Future Value
ROI Calculator
ROI Calculator
IRR Calculator
IRR Calculator
Payback Period
Payback Period
Average Return
Average Return
GDP Calculator
GDP Calculator
Web marketing and ad metric calculators
CTR Calculator
CTR Calculator
Conversion Rate
Conversion Rate
CPC, CPM & CPA
CPC, CPM & CPA
ROAS Calculator
ROAS Calculator
Break-Even CPA
Break-Even CPA
LTV Calculator
LTV Calculator
CAC Calculator
CAC Calculator
Churn Rate
Churn Rate
A/B Test Calc
A/B Test Calc
A/B Sample Size
A/B Sample Size
SEO Traffic
SEO Traffic
Break-Even Point
Break-Even Point
Markup vs. Margin
Markup vs. Margin
CAGR Calculator
CAGR Calculator
Health and fitness calculators
BMI Calculator
BMI Calculator
Sleep Calculator
Sleep Calculator
Calorie Calculator
Calorie Calculator
BMR Calculator
BMR Calculator
TDEE Calculator
TDEE Calculator
Ideal Weight
Ideal Weight
Body Fat Calculator
Body Fat Calculator
Lean Body Mass
Lean Body Mass
Calories Burned
Calories Burned
Protein Intake
Protein Intake
Macro Calculator
Macro Calculator
Carb Calculator
Carb Calculator
Fat Intake
Fat Intake
Child Height
Child Height
Sports calculators
Golf Handicap
Golf Handicap
Pace Calculator
Pace Calculator
1RM Calculator
1RM Calculator
Target Heart Rate
Target Heart Rate
Weather calculators
Heat Index
Heat Index
Wind Chill
Wind Chill
Dew Point
Dew Point
Computer calculators
Base Converter
Base Converter
Subnet Calculator
Subnet Calculator
Download Time
Download Time
Household energy and budget calculators
Electricity Cost
Electricity Cost
kWh to Cost
kWh to Cost
Yearly kWh to Cost
Yearly kWh to Cost
AC Size (BTU)
AC Size (BTU)
AC Running Cost
AC Running Cost
Heating Costs
Heating Costs
Gas vs Electric
Gas vs Electric
LED Savings
LED Savings
Salary Calculator
Salary Calculator
Budget Calculator
Budget Calculator
Car calculators
Trip Gas Cost
Trip Gas Cost
EV Charging Cost
EV Charging Cost
EV vs Gas Cost
EV vs Gas Cost
MPG Calculator
MPG Calculator
Tire Size
Tire Size
Solar power and battery calculators
Solar Output
Solar Output
Solar Panel Count
Solar Panel Count
Solar Payback
Solar Payback
Battery Size
Battery Size
Home and DIY calculators
Tile Calculator
Tile Calculator
Stair Calculator
Stair Calculator
Concrete Volume
Concrete Volume
Wall Area
Wall Area
Wallpaper Rolls
Wallpaper Rolls
Paint Calculator
Paint Calculator
Flooring Needed
Flooring Needed
Exterior Walls
Exterior Walls
Gravel Needed
Gravel Needed
Mortar Mix
Mortar Mix
Slope Grade
Slope Grade
Lumber Cut List
Lumber Cut List
Lot Coverage/FAR
Lot Coverage/FAR
Sheet Vinyl Roll
Sheet Vinyl Roll
Insulation Needed
Insulation Needed
Curtain Size
Curtain Size
TV Size & Distance
TV Size & Distance
Soil Needed
Soil Needed
Sod Needed
Sod Needed
Block Calculator
Block Calculator
Brick Calculator
Brick Calculator
Deck Materials
Deck Materials
Ramp Length
Ramp Length
Pilot Hole Size
Pilot Hole Size
Room Ventilation
Room Ventilation
Paint Thinning
Paint Thinning
Baseboard & Trim
Baseboard & Trim
Blind Size
Blind Size
Picture Hanging
Picture Hanging
Drain Slope
Drain Slope
Screw Calculator
Screw Calculator
Board Feet
Board Feet
Fence Calculator
Fence Calculator
Wood Shrinkage
Wood Shrinkage
Caulk Calculator
Caulk Calculator
Heat Loss
Heat Loss
Furniture Fit
Furniture Fit
Moving Boxes
Moving Boxes
Storage Capacity
Storage Capacity
Plywood Cuts
Plywood Cuts
Shelf Sag
Shelf Sag

NumberChef

Free Online Calculators for Everyday Math

NumberChef is a collection of free calculators for everyday life, school and work, from probability and statistics to money, health and DIY.

Type in your numbers, press "Calculate", and the result appears right away.

Each page is more than a calculator: it also explains the formula itself, gives you the same calculation as Excel and Google Sheets formulas and as Python code, and lists what you need to know to understand the math, so you can use the calculation with confidence.

There is no sign-up, no login and nothing to download. Just open the page and start calculating.

All you need is a browser and an internet connection, on a PC or a smartphone.
Probability and random number calculators
Independent Events
Independent Events
Two Events Solver
Two Events Solver
Repeated Trials
Repeated Trials
Bayes' Theorem
Bayes' Theorem
Expected Value
Expected Value
Binomial Distribution
Binomial Distribution
nPr and nCr
nPr and nCr
Circular Permutation
Circular Permutation
With Repetition
With Repetition
Random Number
Random Number
Averages and statistics calculators
Average Calculator
Average Calculator
Mean Median Mode
Mean Median Mode
SD Calculator
SD Calculator
Quartiles & IQR
Quartiles & IQR
Frequency Table
Frequency Table
Correlation (r)
Correlation (r)
Normal Probability
Normal Probability
Z-Score Calculator
Z-Score Calculator
Confidence Interval
Confidence Interval
Sample Size
Sample Size
Mark & Recapture
Mark & Recapture
P-Value Calculator
P-Value Calculator
Percentage and ratio calculators
Percentage Calc
Percentage Calc
Percent Change
Percent Change
Percent Difference
Percent Difference
Percent Error
Percent Error
Ratio Calculator
Ratio Calculator
Discount Calculator
Discount Calculator
Sales Tax Calculator
Sales Tax Calculator
Margin Calculator
Margin Calculator
Speed calculators
Speed Calculator
Speed Calculator
Density and concentration calculators
Density
Density
Molarity
Molarity
Molar Mass
Molar Mass
Physics and electricity calculators
Ohm's Law
Ohm's Law
Watts to Amps
Watts to Amps
Resistor Colors
Resistor Colors
Voltage Drop
Voltage Drop
Unit conversion calculators
Weight Converter
Weight Converter
Shoe Size Converter
Shoe Size Converter
Integer and signed number calculators
Long Division
Long Division
LCM Calculator
LCM Calculator
GCF Calculator
GCF Calculator
Integer Calculator
Integer Calculator
Prime Factorization
Prime Factorization
Diophantine Solver
Diophantine Solver
Modulo Calculator
Modulo Calculator
Factor Calculator
Factor Calculator
Roman Numerals
Roman Numerals
Fraction, decimal and rounding calculators
Fraction Calculator
Fraction Calculator
Mixed Numbers
Mixed Numbers
Simplify Fractions
Simplify Fractions
Fraction to Decimal
Fraction to Decimal
Decimal to Fraction
Decimal to Fraction
Rounding
Rounding
Equation and inequality calculators
Linear Equation
Linear Equation
Linear Systems
Linear Systems
Quadratic Formula
Quadratic Formula
Absolute Value
Absolute Value
Quadratic Inequality
Quadratic Inequality
Polynomial calculators
Binomial Theorem
Binomial Theorem
Square root and nth root calculators
Simplify Radicals
Simplify Radicals
Nth Root
Nth Root
Exponent and logarithm calculators
Exponents
Exponents
Log Calculator
Log Calculator
Number of Digits
Number of Digits
Scientific Notation
Scientific Notation
Sci. Notation Math
Sci. Notation Math
Half-Life
Half-Life
Complex number calculators
Complex Numbers
Complex Numbers
Polar Form
Polar Form
De Moivre
De Moivre
Function and graph calculators
Slope Calculator
Slope Calculator
Linear Function
Linear Function
Direct & Inverse Variation
Direct & Inverse Variation
y = ax² Calculator
y = ax² Calculator
Distance Formula
Distance Formula
3D Distance
3D Distance
Section Formula
Section Formula
Point to Line
Point to Line
Lat/Long Distance
Lat/Long Distance
Complete the Square
Complete the Square
Circle Equation
Circle Equation
Conic Sections
Conic Sections
Polar Coordinates
Polar Coordinates
Sequence calculators
Arithmetic Sequence
Arithmetic Sequence
Geometric Sequence
Geometric Sequence
Fibonacci Sequence
Fibonacci Sequence
Recurrence Relation
Recurrence Relation
Vector calculators
Vector Calculator
Vector Calculator
Cross Product
Cross Product
Matrix calculators
Matrix Calculator
Matrix Calculator
Determinant
Determinant
Inverse Matrix
Inverse Matrix
Plane geometry calculators
Sin Cos Tan
Sin Cos Tan
Degrees ⇔ Radians
Degrees ⇔ Radians
a sin θ + b cos θ
a sin θ + b cos θ
Triangle Solver
Triangle Solver
Triangle Area
Triangle Area
Right Triangle
Right Triangle
Pythagorean Theorem
Pythagorean Theorem
Polygon Angles
Polygon Angles
Scale Factor
Scale Factor
Parallel Lines
Parallel Lines
Rectangle Area
Rectangle Area
Parallelogram Area
Parallelogram Area
Trapezoid Area
Trapezoid Area
Circle Calculator
Circle Calculator
Sector Area
Sector Area
Inscribed Angle
Inscribed Angle
Ellipse Area
Ellipse Area
Solid geometry calculators
Cube Volume
Cube Volume
Cube Surface Area
Cube Surface Area
Box Volume
Box Volume
Box Surface Area
Box Surface Area
Cylinder Volume
Cylinder Volume
Cylinder Surface
Cylinder Surface
Sphere Volume
Sphere Volume
Sphere Surface
Sphere Surface
Spherical Cap Volume
Spherical Cap Volume
Cap Surface Area
Cap Surface Area
Ellipsoid Volume
Ellipsoid Volume
Ellipsoid Surface
Ellipsoid Surface
Pyramid Volume
Pyramid Volume
Pyramid Surface
Pyramid Surface
Cone Volume
Cone Volume
Cone Surface Area
Cone Surface Area
Frustum Volume
Frustum Volume
Frustum Surface Area
Frustum Surface Area
Pipe Volume
Pipe Volume
Capsule Volume
Capsule Volume
Capsule Surface Area
Capsule Surface Area
Date and time calculators
Age Calculator
Age Calculator
Days Between Dates
Days Between Dates
Date Calculator
Date Calculator
Hours From Now
Hours From Now
Day of the Week
Day of the Week
Time Calculator
Time Calculator
Time Zone Converter
Time Zone Converter
Hours Calculator
Hours Calculator
Time Duration
Time Duration
Time Card
Time Card
Finance and economics calculators
Compound Interest
Compound Interest
Simple Interest
Simple Interest
Interest Calculator
Interest Calculator
TVM Calculator
TVM Calculator
Present Value
Present Value
Future Value
Future Value
ROI Calculator
ROI Calculator
IRR Calculator
IRR Calculator
Payback Period
Payback Period
Average Return
Average Return
GDP Calculator
GDP Calculator
Web marketing and ad metric calculators
CTR Calculator
CTR Calculator
Conversion Rate
Conversion Rate
CPC, CPM & CPA
CPC, CPM & CPA
ROAS Calculator
ROAS Calculator
Break-Even CPA
Break-Even CPA
LTV Calculator
LTV Calculator
CAC Calculator
CAC Calculator
Churn Rate
Churn Rate
A/B Test Calc
A/B Test Calc
A/B Sample Size
A/B Sample Size
SEO Traffic
SEO Traffic
Break-Even Point
Break-Even Point
Markup vs. Margin
Markup vs. Margin
CAGR Calculator
CAGR Calculator
Health and fitness calculators
BMI Calculator
BMI Calculator
Sleep Calculator
Sleep Calculator
Calorie Calculator
Calorie Calculator
BMR Calculator
BMR Calculator
TDEE Calculator
TDEE Calculator
Ideal Weight
Ideal Weight
Body Fat Calculator
Body Fat Calculator
Lean Body Mass
Lean Body Mass
Calories Burned
Calories Burned
Protein Intake
Protein Intake
Macro Calculator
Macro Calculator
Carb Calculator
Carb Calculator
Fat Intake
Fat Intake
Child Height
Child Height
Sports calculators
Golf Handicap
Golf Handicap
Pace Calculator
Pace Calculator
1RM Calculator
1RM Calculator
Target Heart Rate
Target Heart Rate
Weather calculators
Heat Index
Heat Index
Wind Chill
Wind Chill
Dew Point
Dew Point
Computer calculators
Base Converter
Base Converter
Subnet Calculator
Subnet Calculator
Download Time
Download Time
Household energy and budget calculators
Electricity Cost
Electricity Cost
kWh to Cost
kWh to Cost
Yearly kWh to Cost
Yearly kWh to Cost
AC Size (BTU)
AC Size (BTU)
AC Running Cost
AC Running Cost
Heating Costs
Heating Costs
Gas vs Electric
Gas vs Electric
LED Savings
LED Savings
Salary Calculator
Salary Calculator
Budget Calculator
Budget Calculator
Car calculators
Trip Gas Cost
Trip Gas Cost
EV Charging Cost
EV Charging Cost
EV vs Gas Cost
EV vs Gas Cost
MPG Calculator
MPG Calculator
Tire Size
Tire Size
Solar power and battery calculators
Solar Output
Solar Output
Solar Panel Count
Solar Panel Count
Solar Payback
Solar Payback
Battery Size
Battery Size
Home and DIY calculators
Tile Calculator
Tile Calculator
Stair Calculator
Stair Calculator
Concrete Volume
Concrete Volume
Wall Area
Wall Area
Wallpaper Rolls
Wallpaper Rolls
Paint Calculator
Paint Calculator
Flooring Needed
Flooring Needed
Exterior Walls
Exterior Walls
Gravel Needed
Gravel Needed
Mortar Mix
Mortar Mix
Slope Grade
Slope Grade
Lumber Cut List
Lumber Cut List
Lot Coverage/FAR
Lot Coverage/FAR
Sheet Vinyl Roll
Sheet Vinyl Roll
Insulation Needed
Insulation Needed
Curtain Size
Curtain Size
TV Size & Distance
TV Size & Distance
Soil Needed
Soil Needed
Sod Needed
Sod Needed
Block Calculator
Block Calculator
Brick Calculator
Brick Calculator
Deck Materials
Deck Materials
Ramp Length
Ramp Length
Pilot Hole Size
Pilot Hole Size
Room Ventilation
Room Ventilation
Paint Thinning
Paint Thinning
Baseboard & Trim
Baseboard & Trim
Blind Size
Blind Size
Picture Hanging
Picture Hanging
Drain Slope
Drain Slope
Screw Calculator
Screw Calculator
Board Feet
Board Feet
Fence Calculator
Fence Calculator
Wood Shrinkage
Wood Shrinkage
Caulk Calculator
Caulk Calculator
Heat Loss
Heat Loss
Furniture Fit
Furniture Fit
Moving Boxes
Moving Boxes
Storage Capacity
Storage Capacity
Plywood Cuts
Plywood Cuts
Shelf Sag
Shelf Sag

NumberChef Calculators List

Probability and random number

Probability of Two Events (And, Or, Neither)
Probability of Two Events (And, Or, Neither)
Free calculator for two independent events: P(A and B), P(A or B), exactly one, and neither, from P(A) and P(B). With Venn diagram, Excel and Python.
Probability of Two Events Solver
Probability of Two Events Solver
Free solver for two independent events: enter any 2 of 8 probabilities, like P(A and B) and P(A or B), and get all the rest, with every step shown.
Probability of Repeated Trials (n in a Row, At Least Once)
Probability of Repeated Trials (n in a Row, At Least Once)
Free calculator for repeated trials: the chance something happens at least once, n times in a row, or never in n tries. Formulas, Excel and Python.
Conditional Probability and Bayes' Theorem Calculator
Conditional Probability and Bayes' Theorem Calculator
Free calculator for conditional probability P(B|A) and Bayes' theorem P(A|B), with steps, a tree diagram and exact fractions. Enter 0.3, 30% or 3/10.
Expected Value Calculator (Mean, Variance, Standard Deviation)
Expected Value Calculator (Mean, Variance, Standard Deviation)
Free expected value calculator: enter values and probabilities to get E(X), variance and standard deviation, with exact fractions, steps and a graph.
Binomial Distribution Calculator
Binomial Distribution Calculator
Free binomial probability calculator. Find P(X=k), P(X≤k) and P(X≥k), the mean np, variance and standard deviation, with exact fractions and a bar chart.
Permutation and Combination Calculator (nPr, nCr)
Permutation and Combination Calculator (nPr, nCr)
Free permutation and combination calculator. Enter n and r to get nPr and nCr, with huge answers shown to every digit. Formulas, Excel and Python included.
Circular Permutation Calculator (Round Table and Necklace)
Circular Permutation Calculator (Round Table and Necklace)
Free circular permutation calculator with steps. Find (n−1)! for a round table, nPr/r, necklace arrangements (n−1)!/2 and 2 people seated together or not.
Permutations and Combinations with Repetition Calculator
Permutations and Combinations with Repetition Calculator
Free calculator for permutations with repetition (n^r), combinations with repetition (stars and bars) and word rearrangements like TOMATO, with diagrams.
Random Number Generator
Random Number Generator
Free random number generator for any range. Whole numbers or decimals, up to 999 at once, with a no-repeats option and sorting. Excel and Python included.

Averages and statistics

Average Calculator (Mean)
Average Calculator (Mean)
Free average calculator. Enter numbers separated by commas to get the mean, plus the sum, count, median, geometric mean, max, min and range.
Mean, Median, Mode and Range Calculator
Mean, Median, Mode and Range Calculator
Free calculator for the mean, median, mode and range of a data set. Finds multiple modes or no mode, and explains when to use each measure.
Standard Deviation Calculator for Population and Sample
Standard Deviation Calculator for Population and Sample
Free standard deviation calculator. Get the population SD σ and sample SD s, plus the variance, mean and sum of squares. Learn when to divide by N or N−1.
Quartile and Box Plot Calculator (Q1, Q2, Q3, IQR, Outliers)
Quartile and Box Plot Calculator (Q1, Q2, Q3, IQR, Outliers)
Free quartile calculator. Get Q1, the median, Q3, the IQR, the five-number summary and outliers (1.5×IQR rule), and draw a box plot instantly, with steps.
Frequency Distribution Table Calculator (Relative and Cumulative Frequency, Histogram)
Frequency Distribution Table Calculator (Relative and Cumulative Frequency, Histogram)
Free frequency table maker. Paste raw data to get classes, midpoints, relative and cumulative frequency, an estimated mean and a histogram.
Correlation Coefficient and Covariance Calculator (with Scatter Plot and Regression Line)
Correlation Coefficient and Covariance Calculator (with Scatter Plot and Regression Line)
Free correlation coefficient calculator. Enter paired x and y data to get r, the covariance, the regression line and a scatter plot, with steps.
Normal Distribution Probability Calculator
Normal Distribution Probability Calculator
Free normal distribution calculator. Enter the mean and standard deviation to get the probability between two values or above a value, with a z table.
Z-Score Calculator: Z-Score to Probability and Back
Z-Score Calculator: Z-Score to Probability and Back
Free z-score calculator: z-score from a value, mean and SD, z-score to probability and back (no z table needed), and the probability between two z-scores.
Confidence Interval Calculator for a Population Mean
Confidence Interval Calculator for a Population Mean
Free confidence interval calculator. Enter the sample size, mean, SD and confidence level to get the interval and margin of error, with a 90/95/99% table.
Sample Size Calculator (Surveys and Margin of Error)
Sample Size Calculator (Surveys and Margin of Error)
Free sample size calculator for surveys and polls. Find how many people you need from the confidence level and margin of error, or the error from n.
Population Estimate Calculator (Mark and Recapture, Random Samples)
Population Estimate Calculator (Mark and Recapture, Random Samples)
Free capture-recapture calculator. Estimate a population from marked animals, or a total count from a random sample, with step-by-step proportions.
P-Value Calculator: Z-Score to P-Value and Back
P-Value Calculator: Z-Score to P-Value and Back
Free p-value calculator. Get one- and two-tailed p-values from a z test statistic, or the critical z from a p-value, with hypothesis tests explained.

Percentage and ratio

Percentage Calculator (Percent, Part and Whole)
Percentage Calculator (Percent, Part and Whole)
Free percentage calculator: what is 20% of 5000? 10 is what percent of 50? 25 is 10% of what? Enter two values to get the third. Formulas, Excel, Python.
Percentage Change Calculator (Increase and Decrease)
Percentage Change Calculator (Increase and Decrease)
Free percent increase and decrease calculator: Enter two of original value, percent change and new value to get the third, even a price before a discount.
Percent Difference Calculator
Percent Difference Calculator
Free percentage difference calculator: the difference of two values divided by their average, × 100. Also shows percent change and how the two differ.
Percent Error Calculator (Absolute and Relative Error)
Percent Error Calculator (Absolute and Relative Error)
Free percent error calculator: enter the measured and true values to get percent error, error, absolute error and relative error, with a graph.
Ratio and Proportion Calculator (Solve A:B = C:D, Scale a Ratio)
Ratio and Proportion Calculator (Solve A:B = C:D, Scale a Ratio)
Free ratio calculator. Solve a proportion like 3:4 = 600:x by cross multiplying, scale a ratio up or down, and see it as 1:n or m:1. Excel formulas too.
Discount Calculator (Sale Price, Amount Off and Percent Off)
Discount Calculator (Sale Price, Amount Off and Percent Off)
Free discount calculator. Find the sale price, amount off, percent off or original price from any two values. Handles an extra % off too, with formulas.
Sales Tax Calculator (Add or Remove Sales Tax and VAT)
Sales Tax Calculator (Add or Remove Sales Tax and VAT)
Free sales tax calculator. Enter any two of pre-tax price, tax rate and total price to get the third and the tax amount. Reverse sales tax and VAT too.
Profit Margin Calculator (Cost, Revenue, Profit and Markup)
Profit Margin Calculator (Cost, Revenue, Profit and Markup)
Free profit margin calculator. Enter any two of cost, revenue, margin and profit to get the rest plus markup, with a pie chart and formulas.

Speed

Speed, Distance and Time Calculator
Speed, Distance and Time Calculator
Free speed, distance and time calculator. Enter any two values to get the third, with mph converted to ft/min and ft/s. Formulas, Excel and Python too.

Density and concentration

Density Calculator (Density, Mass and Volume)
Density Calculator (Density, Mass and Volume)
Free density calculator. Enter two of density, mass and volume to get the third, with g/cm³, kg/m³, g, kg, mL and L converted. Formulas, Excel, Python.
Molarity Calculator (Mass, Molar Mass, Volume and Concentration)
Molarity Calculator (Mass, Molar Mass, Volume and Concentration)
Free molarity calculator. Enter three of mass, molar mass, volume and molarity (mol/L) to get the fourth, plus moles and g/L. Formulas, Excel, Python.
Molar Mass Calculator (Molecular Weight)
Molar Mass Calculator (Molecular Weight)
Free molar mass calculator. Type a formula like H2O or Al2(SO4)3 to get g/mol, with a breakdown and pie chart of mass percent by element. Handles hydrates.

Physics and electricity

Ohm's Law Calculator (Voltage, Current, Resistance and Power)
Ohm's Law Calculator (Voltage, Current, Resistance and Power)
Free Ohm's law calculator (V = IR, P = VI). Enter two of voltage, current, resistance and power to get the other two, with unit conversion and a V-I graph.
Watts to Amps Calculator (Watts, Volts and Amps)
Watts to Amps Calculator (Watts, Volts and Amps)
Free watts to amps calculator. Enter two of watts, volts and amps to get the third. 120 V and 240 V presets, power factor, and VA vs. watts.
Resistor Color Code Calculator (Resistance and Tolerance from Color Bands)
Resistor Color Code Calculator (Resistance and Tolerance from Color Bands)
Free resistor color code calculator for 3, 4, 5 and 6 bands. Pick the colors to get the resistance, tolerance, min-max range and temperature coefficient.
Voltage Drop Calculator (Wire Size, Length and Current)
Voltage Drop Calculator (Wire Size, Length and Current)
Free voltage drop calculator. Enter AWG wire size, one-way length and current to get the voltage drop, percent drop and end voltage. 1- and 3-phase, DC.

Unit conversion

Weight Converter (lb, kg, oz, g, Carats and More)
Weight Converter (lb, kg, oz, g, Carats and More)
Free weight converter. Convert pounds, ounces, kilograms, grams, milligrams, metric tons and carats all at once, using the exact 1 lb = 0.45359237 kg.
Shoe Size Converter (US, UK, EU, Japan and China)
Shoe Size Converter (US, UK, EU, Japan and China)
Free shoe size converter. Convert US, UK, EU, Japan (cm) and China sizes for men, women, kids and toddlers, with foot length in inches and cm.

Integer and signed number

Long Division Calculator with Remainders (Step by Step)
Long Division Calculator with Remainders (Step by Step)
Free long division calculator that shows the work, with each divide, multiply, subtract and bring down step. Get the remainder, or divide into decimals.
Least Common Multiple (LCM) Calculator
Least Common Multiple (LCM) Calculator
Free LCM calculator. Find the least common multiple of 2, 3 or more numbers with prime factorization steps and the GCF. Excel and Python formulas too.
Greatest Common Factor (GCF / GCD) Calculator
Greatest Common Factor (GCF / GCD) Calculator
Free GCF calculator. Find the greatest common factor (GCD) of 2, 3 or more numbers, with prime factorization steps and the Euclidean algorithm explained.
Positive and Negative Numbers Calculator (Integer Rules, Steps and Number Line)
Positive and Negative Numbers Calculator (Integer Rules, Steps and Number Line)
Free integer calculator for positive and negative numbers like -3+5-(-2), with each step, the sign rules and a number line. Fractions and powers work too.
Prime Factorization Calculator
Prime Factorization Calculator
Free prime factorization calculator. Get the prime factors as a product and in exponent form (2² × 5²), the ladder method steps and the number of factors.
Linear Diophantine Equation Solver (ax + by = c) with Euclidean Algorithm Steps
Linear Diophantine Equation Solver (ax + by = c) with Euclidean Algorithm Steps
Free solver for ax + by = c in integers. Shows the Euclidean algorithm steps, a particular solution, the general solution and positive solutions only.
Modulo Calculator (a mod n, Congruence and Modular Exponentiation)
Modulo Calculator (a mod n, Congruence and Modular Exponentiation)
Free modulo calculator. Find a mod n, check a ≡ b (mod n) and get large powers mod n with repeated squaring steps. Works with negative numbers.
Factor Calculator (All Factors, Number of Factors, Prime Factorization)
Factor Calculator (All Factors, Number of Factors, Prime Factorization)
Free factor calculator. Lists all factors of a number, counts them, and shows factor pairs and the prime factorization. Also tells you if it is prime.
Roman Numeral Converter (Numbers to Roman Numerals and Back)
Roman Numeral Converter (Numbers to Roman Numerals and Back)
Free Roman numeral converter. Turn numbers into Roman numerals and back (1994 = MCMXCIV) step by step. Handles IIII and bars up to 3,999,999.

Fraction, decimal and rounding

Fraction Calculator (Add, Subtract, Multiply and Divide Fractions)
Fraction Calculator (Add, Subtract, Multiply and Divide Fractions)
Free fraction calculator. Add, subtract, multiply and divide fractions with steps. Get the answer in lowest terms, as a mixed number and as a decimal.
Mixed Numbers Calculator (Add, Subtract, Multiply and Divide)
Mixed Numbers Calculator (Add, Subtract, Multiply and Divide)
Free mixed number calculator: add, subtract, multiply and divide mixed numbers with steps. Answers as a simplified fraction, mixed number and decimal.
Simplify Fractions Calculator (Reduce to Lowest Terms)
Simplify Fractions Calculator (Reduce to Lowest Terms)
Free calculator to simplify fractions to lowest terms using the GCF. Works with mixed numbers, negatives and decimals, and shows every step.
Fraction to Decimal Calculator (Numerator ÷ Denominator, Repeating Decimals)
Fraction to Decimal Calculator (Numerator ÷ Denominator, Repeating Decimals)
Free fraction to decimal calculator: what is 2/7 as a decimal? Enter the numerator and denominator. Repeating decimals and negatives OK. Excel, Python.
Decimal to Fraction Calculator (Simplest Form and Mixed Numbers)
Decimal to Fraction Calculator (Simplest Form and Mixed Numbers)
Free decimal to fraction calculator: what is 0.375 as a fraction? Get the simplest form and a mixed number, with steps. Negatives OK. Excel and Python too.
Rounding Calculator (Round, Round Up and Round Down)
Rounding Calculator (Round, Round Up and Round Down)
Free rounding calculator: round to the nearest tenth, whole number or hundred. Shows round up, round down, banker's rounding and more. Excel and Python.

Equation and inequality

Linear Equation Calculator (Solve for x with Steps)
Linear Equation Calculator (Solve for x with Steps)
Free linear equation solver for ax+b=cx+d with steps and a check. Exact fraction and decimal answers, no-solution and infinitely-many cases, and a graph.
System of Equations Calculator (Elimination and Substitution with Steps)
System of Equations Calculator (Elimination and Substitution with Steps)
Free system of equations calculator. Solves two linear equations by elimination or substitution, with steps, a graph and a check.
Quadratic Formula Calculator (Discriminant and Complex Roots)
Quadratic Formula Calculator (Discriminant and Complex Roots)
Free quadratic formula calculator. Enter a, b and c to solve ax²+bx+c=0 with steps. The discriminant shows two real roots, a double root or complex roots.
Absolute Value Equation and Inequality Calculator (Two Methods with Steps and a Number Line)
Absolute Value Equation and Inequality Calculator (Two Methods with Steps and a Number Line)
Free solver for |ax+b| = c, < c, ≤ c, > c and ≥ c. Two methods with steps (the basic rules and splitting into cases), exact fractions and a number line.
Quadratic Inequality Calculator (Solution Set, Discriminant Cases and Graph)
Quadratic Inequality Calculator (Solution Set, Discriminant Cases and Graph)
Free solver for ax²+bx+c > 0, ≥ 0, < 0 or ≤ 0. Steps by the sign of the discriminant, exact answers with simplified radicals, and a graph of the parabola.

Polynomial

Binomial Theorem Calculator (Expansion, Coefficient of a Term, Pascal's Triangle)
Binomial Theorem Calculator (Expansion, Coefficient of a Term, Pascal's Triangle)
Free binomial theorem calculator: expand (Ax+B)^n or find one term, such as the coefficient of x^3, with nCk steps and Pascal's triangle. Exact fractions.

Square root and nth root

Simplify Radicals Calculator (Square Roots, Simplest Radical Form, +, −, ×, ÷)
Simplify Radicals Calculator (Square Roots, Simplest Radical Form, +, −, ×, ÷)
Free calculator to simplify square roots: √48 = 4√3, with prime factorization steps. Add, subtract, multiply and divide radicals, and rationalize.
Nth Root Calculator (Square Root, Cube Root, nth Root)
Nth Root Calculator (Square Root, Cube Root, nth Root)
Free nth root calculator for square roots like √27, cube roots and any nth root, even odd roots of negatives like ∛−8. Formulas, Excel and Python included.

Exponent and logarithm

Exponent Calculator (Powers, a to the nth Power)
Exponent Calculator (Powers, a to the nth Power)
Free exponent calculator for powers like 2^5, negative and decimal exponents and base e. Also solves for the exponent or base. Formulas, Excel, Python.
Logarithm Calculator (Log Calculator)
Logarithm Calculator (Log Calculator)
Free log calculator with any base. Enter two of base, argument and log value to get the third. Covers log10 and ln, log rules, Excel and Python formulas.
Number of Digits Calculator (How Many Digits in 2^100? Leading Digit)
Number of Digits Calculator (How Many Digits in 2^100? Leading Digit)
Find how many digits a power like 2^100 has, free, by hand with log 2 ≈ 0.3010 and exactly. Also finds the leading digit and first nonzero decimal place.
Scientific Notation Converter (b×10ⁿ, E Notation, Engineering Notation)
Scientific Notation Converter (b×10ⁿ, E Notation, Engineering Notation)
Free scientific notation converter. Enter any number or 2.3E+11 to get scientific, E, engineering and decimal notation, with steps for the decimal point.
Scientific Notation Calculator (Add, Subtract, Multiply, Divide, Powers)
Scientific Notation Calculator (Add, Subtract, Multiply, Divide, Powers)
Free calculator to add, subtract, multiply, divide, square and take roots of numbers in scientific notation, like (2×10⁴)×(3×10⁵), with step-by-step rules.
Half-Life Calculator (Initial Amount, Remaining Amount, Time, Half-Life)
Half-Life Calculator (Initial Amount, Remaining Amount, Time, Half-Life)
Free half-life calculator. Enter 3 of initial amount, remaining amount, time and half-life to get the 4th, plus decay constant, mean lifetime and a graph.

Complex number

Complex Number Calculator (Add, Subtract, Multiply and Divide with Steps, Conjugate, Modulus and Complex Plane)
Complex Number Calculator (Add, Subtract, Multiply and Divide with Steps, Conjugate, Modulus and Complex Plane)
Free complex number calculator for a+bi. Add, subtract, multiply and divide with steps, exact fractions, conjugate, modulus and a complex plane graph.
Complex Number to Polar Form Calculator (Modulus, Argument and Quadrant Steps with a Complex Plane Graph)
Complex Number to Polar Form Calculator (Modulus, Argument and Quadrant Steps with a Complex Plane Graph)
Free converter from a+bi to polar form r(cos θ + i sin θ) with steps. Exact modulus and argument as a fraction of π, polar to rectangular too, and a graph.
De Moivre's Theorem Calculator (Powers and nth Roots of Complex Numbers with Steps and a Polygon Graph)
De Moivre's Theorem Calculator (Powers and nth Roots of Complex Numbers with Steps and a Polygon Graph)
Free De Moivre's theorem calculator for powers and nth roots of a+bi, with steps (rⁿ and nθ), exact values, and all n roots drawn as a regular polygon.

Function and graph

Slope Calculator (Slope of a Line, Distance and Angle)
Slope Calculator (Slope of a Line, Distance and Angle)
Free slope calculator. Enter two points to get the slope m, distance, angle, y = mx + b and intercepts. Also finds the point a given distance along a line.
Linear Function Calculator (Find y = mx + b from Two Points or a Slope and a Point, Rate of Change and Intercepts)
Linear Function Calculator (Find y = mx + b from Two Points or a Slope and a Point, Rate of Change and Intercepts)
Free calculator for the equation of a line y = mx + b from two points or a slope and a point. Exact fractions, steps, x- and y-intercepts, and a graph.
Direct and Inverse Variation Calculator (Equation and Constant of Variation from One Point)
Direct and Inverse Variation Calculator (Equation and Constant of Variation from One Point)
Free direct and inverse variation calculator. Enter one point to get y = ax or y = a/x and the constant of variation, with steps, a table and a graph.
Quadratic Function y = ax² Calculator (Range for a Given Domain and Average Rate of Change)
Quadratic Function y = ax² Calculator (Range for a Given Domain and Average Rate of Change)
Free y = ax² calculator: the range of y for a domain of x, the average rate of change, and y for any x. Step-by-step, with a graph.
Distance Between Two Points Calculator (Distance Formula, Slope and Equation of the Line)
Distance Between Two Points Calculator (Distance Formula, Slope and Equation of the Line)
Free distance formula calculator. Enter two points to get the distance between them, plus the slope and the equation of the line, with steps and a graph.
3D Distance Calculator (Distance Between Two Points in Space from xyz Coordinates)
3D Distance Calculator (Distance Between Two Points in Space from xyz Coordinates)
Free 3D distance calculator. Enter the xyz coordinates of two points to get the distance between them in space, with steps and a 3D figure you can rotate.
Section Formula Calculator (Internal and External Division, Midpoint and Centroid)
Section Formula Calculator (Internal and External Division, Midpoint and Centroid)
Free section formula calculator: the point dividing AB internally or externally in m:n, the midpoint or the centroid, in 1D, 2D or 3D, as fractions.
Distance from a Point to a Line Calculator (Foot of the Perpendicular and Parallel Lines)
Distance from a Point to a Line Calculator (Foot of the Perpendicular and Parallel Lines)
Free distance from a point to a line ax+by+c=0 as an exact value and a decimal, with the foot of the perpendicular, steps and a graph. Parallel lines too.
Latitude and Longitude Distance Calculator (Decimal and DMS)
Latitude and Longitude Distance Calculator (Decimal and DMS)
Free distance between two latitude/longitude points in miles and km. Decimal or DMS input, calculated on the Earth's ellipsoid with Lambert's formula.
Completing the Square Calculator (Vertex, Axis of Symmetry, Max and Min)
Completing the Square Calculator (Vertex, Axis of Symmetry, Max and Min)
Free completing the square calculator. Turn y=ax²+bx+c into vertex form with steps, and get the vertex, axis of symmetry, max or min and a graph.
Equation of a Circle Calculator (General and Standard Form, Center, Radius, Circle and Line)
Equation of a Circle Calculator (General and Standard Form, Center, Radius, Circle and Line)
Free circle equation calculator. Convert general form to standard form with steps, get the exact center and radius, and find where a line meets the circle.
Conic Sections Calculator (Foci, Directrix and Eccentricity of Ellipses, Hyperbolas and Parabolas)
Conic Sections Calculator (Foci, Directrix and Eccentricity of Ellipses, Hyperbolas and Parabolas)
Free foci, vertices, eccentricity, asymptotes and directrix of an ellipse, hyperbola or parabola, with steps, exact values like (±√5, 0) and a graph.
Polar and Rectangular Coordinates Converter (r and θ, Quadrant Steps and a Graph)
Polar and Rectangular Coordinates Converter (r and θ, Quadrant Steps and a Graph)
Free converter between rectangular (x, y) and polar (r, θ) coordinates. Exact r and θ with quadrant steps, input in degrees or radians, and a graph.

Sequence

Arithmetic Sequence Calculator (nth Term and Sum)
Arithmetic Sequence Calculator (nth Term and Sum)
Free arithmetic sequence calculator. Enter the first term, common difference and number of terms to get the nth term and the sum, with steps and a graph.
Geometric Sequence Calculator (nth Term and Sum)
Geometric Sequence Calculator (nth Term and Sum)
Free geometric sequence calculator. Get the nth term, the sum of the first n terms and the infinite series sum (when |r| < 1), with steps and a graph.
Fibonacci Sequence Calculator (nth Term and Sum)
Fibonacci Sequence Calculator (nth Term and Sum)
Free Fibonacci calculator. Enter n to get the nth Fibonacci number and the sum of the first n terms, exact up to term 1000, with steps and a graph.
Recurrence Relation Calculator (General Term with Steps)
Recurrence Relation Calculator (General Term with Steps)
Free solver for a(n+1) = p·a(n) + q. Get the general term (explicit formula) with steps, exact fractions, a table of terms 1–10, a graph and the limit.

Vector

Vector Calculator (Sum, Difference, Magnitude, Dot Product and Angle)
Vector Calculator (Sum, Difference, Magnitude, Dot Product and Angle)
Free 2D and 3D vector calculator. Get the sum, difference, ka+lb, magnitude, dot product, angle, unit vector and perpendicular/parallel check, with steps.
Cross Product Calculator (Components, Parallelogram Area, Normal Vector)
Cross Product Calculator (Components, Parallelogram Area, Normal Vector)
Free cross product calculator for 3D vectors a×b with steps. Also finds the parallelogram and triangle area, unit normal vector and angle, with a 3D graph.

Matrix

Matrix Calculator (Add, Subtract, Multiply, Transpose, Power)
Matrix Calculator (Add, Subtract, Multiply, Transpose, Power)
Free matrix calculator for 2×2 to 4×4 matrices. Add, subtract, multiply, transpose and raise to a power, with steps showing how row × column works.
Determinant Calculator (2×2, 3×3, 4×4)
Determinant Calculator (2×2, 3×3, 4×4)
Free determinant calculator for 2×2 to 4×4 matrices, with steps for ad − bc, the rule of Sarrus and cofactor expansion. Also checks if it is invertible.
Inverse Matrix Calculator (2×2, 3×3, 4×4)
Inverse Matrix Calculator (2×2, 3×3, 4×4)
Free inverse matrix calculator for 2×2 to 4×4 matrices. Checks if the inverse exists with det(A) and shows steps with the 2×2 formula or the adjugate.

Plane geometry

Sin Cos Tan Calculator (Trig Ratios and Angles with a Unit Circle)
Sin Cos Tan Calculator (Trig Ratios and Angles with a Unit Circle)
Free sin, cos and tan calculator. Exact values like √3/2 for special angles, the angle from a trig value (0° to 180°) and a unit circle diagram.
Degrees to Radians Converter (Exact Answers in Terms of π, with a Unit Circle)
Degrees to Radians Converter (Exact Answers in Terms of π, with a Unit Circle)
Free degrees to radians converter and back. Exact answers in terms of π like 30° = π/6 plus decimals. Enter π/6 or 1.5, with a unit circle diagram.
Harmonic Addition Calculator (a sin θ + b cos θ as R sin(θ + α), with Max and Min)
Harmonic Addition Calculator (a sin θ + b cos θ as R sin(θ + α), with Max and Min)
Free calculator that writes a sin θ + b cos θ as one sine wave R sin(θ + α). Exact R = √(a² + b²), α as a fraction of π, max and min, with a graph.
Triangle Calculator (Solve for Sides, Angles, Area and More)
Triangle Calculator (Solve for Sides, Angles, Area and More)
Free triangle solver. Enter any 3 sides or angles (at least 1 side) to get the rest, plus area, perimeter, heights, medians, inradius and circumradius.
Triangle Area Calculator (from Three Sides with Heron's Formula)
Triangle Area Calculator (from Three Sides with Heron's Formula)
Free triangle area calculator. Enter the three side lengths to get the area with Heron's formula, no height needed. Shows the semiperimeter s too.
Right Triangle Calculator (Sides, Angles, Area and Height from Any Two Values)
Right Triangle Calculator (Sides, Angles, Area and Height from Any Two Values)
Free right triangle solver. Enter any 2 values (sides, an angle, area or perimeter) to get all sides, angles in degrees and radians, area and height.
Pythagorean Theorem Calculator (Hypotenuse and Legs of a Right Triangle)
Pythagorean Theorem Calculator (Hypotenuse and Legs of a Right Triangle)
Free Pythagorean theorem calculator. Enter two sides of a right triangle to find the third with a²+b²=c², plus the angles, area and perimeter, with steps.
Polygon Angle Calculator (Sum of Interior and Exterior Angles, Regular Polygons)
Polygon Angle Calculator (Sum of Interior and Exterior Angles, Regular Polygons)
Free polygon angle calculator. Find the sum of interior angles 180°×(n−2), each angle of a regular polygon, or the number of sides from one angle.
Scale Factor Calculator for Similar Figures (Area Ratio, Volume Ratio and Map Scale)
Scale Factor Calculator for Similar Figures (Area Ratio, Volume Ratio and Map Scale)
Free scale factor calculator. From m:n, get the area ratio m²:n² and volume ratio m³:n³, convert values between similar figures, and use map scales.
Parallel Lines and Angles Calculator (Corresponding, Alternate Interior and Vertical Angles)
Parallel Lines and Angles Calculator (Corresponding, Alternate Interior and Vertical Angles)
Free parallel lines angle calculator. Enter one angle to get all 8 angles made by a transversal, with corresponding, alternate and vertical angles colored.
Area of a Rectangle Calculator (Length × Width)
Area of a Rectangle Calculator (Length × Width)
Free rectangle area calculator. Enter the length and width to get the area (length × width), with square inches and square feet converted for you.
Area of a Parallelogram Calculator (Base × Height)
Area of a Parallelogram Calculator (Base × Height)
Free parallelogram area calculator. Enter the base and height to get the area (base × height), with a figure that shows which lengths to use.
Area of a Trapezoid Calculator ((a + b) × h ÷ 2)
Area of a Trapezoid Calculator ((a + b) × h ÷ 2)
Free trapezoid area calculator. Enter the two bases and the height to get the area with steps, or find the height from the area. Excel and Python included.
Circle Calculator (Radius, Diameter, Circumference and Area)
Circle Calculator (Radius, Diameter, Circumference and Area)
Free circle calculator. Enter any one of radius, diameter, circumference or area to get the other three, with steps. C = 2πR and A = πR² explained.
Area of a Sector Calculator (from Radius and Central Angle)
Area of a Sector Calculator (from Radius and Central Angle)
Free sector area calculator. Enter the radius and central angle (degrees or radians) to get the area, the exact form in π and a figure, with steps.
Inscribed Angle Theorem Calculator (Central Angle, Arc Ratio, Inscribed Quadrilateral)
Inscribed Angle Theorem Calculator (Central Angle, Arc Ratio, Inscribed Quadrilateral)
Free inscribed angle calculator. Central angle from an inscribed angle and back, angles from arc ratios, opposite angles of an inscribed quadrilateral.
Area of an Ellipse Calculator (π × Semi-Major Axis × Semi-Minor Axis)
Area of an Ellipse Calculator (π × Semi-Major Axis × Semi-Minor Axis)
Free ellipse area calculator. Enter the semi-major and semi-minor axes to get the area of an ellipse or oval (π × a × b), plus the exact form such as 600π.

Solid geometry

Volume of a Cube Calculator (Side × Side × Side)
Volume of a Cube Calculator (Side × Side × Side)
Free cube volume calculator. Enter the side length to get the volume (side cubed), converted to gallons and cubic feet, with a 3D figure you can rotate.
Surface Area of a Cube Calculator (6 × Side × Side)
Surface Area of a Cube Calculator (6 × Side × Side)
Free cube surface area calculator. Enter the side length to get the surface area (6 × side²), the area of one face and in² to ft², with a 3D figure.
Rectangular Prism Volume Calculator (Length × Width × Height)
Rectangular Prism Volume Calculator (Length × Width × Height)
Free rectangular prism (box) volume calculator. Enter length, width and height to get the volume in cubic inches, cubic feet and gallons. 3D view included.
Rectangular Prism Surface Area Calculator (from Length, Width and Height)
Rectangular Prism Surface Area Calculator (from Length, Width and Height)
Free box surface area calculator. Enter length, width and height to get the total area of all 6 faces in in² and ft², plus a 3D view and formulas.
Cylinder Volume Calculator (V = πr²h)
Cylinder Volume Calculator (V = πr²h)
Free cylinder volume calculator. Enter the radius and height to get the volume (V = πr²h) in cubic inches, gallons and cubic feet, with a 3D view.
Cylinder Surface Area Calculator (S = 2πr(r + h))
Cylinder Surface Area Calculator (S = 2πr(r + h))
Free cylinder surface area calculator. Enter the radius and height to get the surface area, base area and lateral area in in² and ft², with a 3D view.
Sphere Volume Calculator (V = 4/3 × π × r³)
Sphere Volume Calculator (V = 4/3 × π × r³)
Free sphere volume calculator. Enter the radius to get the volume (4/3 × π × r³) in cubic inches, gallons and cubic feet, plus a 3D view.
Sphere Surface Area Calculator (S = 4 × π × r²)
Sphere Surface Area Calculator (S = 4 × π × r²)
Free sphere surface area calculator. Enter the radius to get the surface area (4 × π × r²) in square inches and square feet, plus a 3D view.
Spherical Cap Volume Calculator (V = πh²(3R − h) ÷ 3)
Spherical Cap Volume Calculator (V = πh²(3R − h) ÷ 3)
Free spherical cap volume calculator with a 3D view. Enter two of base radius, sphere radius and height to get the third and the volume. Excel and Python.
Spherical Cap Surface Area Calculator (Curved Surface Area = 2πRh)
Spherical Cap Surface Area Calculator (Curved Surface Area = 2πRh)
Free spherical cap surface area calculator with 3D view. Enter two of base radius, sphere radius and height to get the curved area 2πRh, base and total.
Ellipsoid Volume Calculator (V = 4/3 πabc)
Ellipsoid Volume Calculator (V = 4/3 πabc)
Free ellipsoid volume calculator. Enter semi-axes a, b and c to get V = 4/3 πabc, with a rotatable 3D view and the volume in gallons. Excel and Python.
Ellipsoid Surface Area Calculator (Thomsen's Approximation)
Ellipsoid Surface Area Calculator (Thomsen's Approximation)
Free ellipsoid surface area calculator. Enter semi-axes a, b and c to get the surface area by Thomsen's formula (error within ±1.06%), with a 3D view.
Square Pyramid Volume Calculator (Base Area × Height ÷ 3)
Square Pyramid Volume Calculator (Base Area × Height ÷ 3)
Free square pyramid volume calculator. Enter the base side and height to get V = side × side × height ÷ 3, with a 3D view and why we divide by 3.
Square Pyramid Surface Area Calculator (Base Area + Lateral Area)
Square Pyramid Surface Area Calculator (Base Area + Lateral Area)
Free square pyramid surface area calculator. Enter the base side and height to get base area + lateral area, with slant height, steps and a 3D view.
Volume of a Cone Calculator (from Radius and Height)
Volume of a Cone Calculator (from Radius and Height)
Free cone volume calculator. Enter the radius and height to get V = 1/3πr²h with a 3D view, in³, ft³ and gallons, and why a cone is 1/3 of a cylinder.
Surface Area of a Cone Calculator (from Radius and Height)
Surface Area of a Cone Calculator (from Radius and Height)
Free cone surface area calculator. Enter the radius and height to get the total area πr² + πrl, base and lateral areas and slant height, with a 3D view.
Volume of a Frustum Calculator (Truncated Cone, from Top and Bottom Radii and Height)
Volume of a Frustum Calculator (Truncated Cone, from Top and Bottom Radii and Height)
Free frustum of a cone volume calculator. Enter the top and bottom radii and height of a bucket, pot or cup to get the volume and gallons, with a 3D view.
Surface Area of a Frustum Calculator (Truncated Cone, from Top and Bottom Radii and Height)
Surface Area of a Frustum Calculator (Truncated Cone, from Top and Bottom Radii and Height)
Free frustum of a cone surface area calculator. Enter the top and bottom radii and height to get the total, top, bottom and lateral areas and slant height.
Pipe Volume Calculator (Hollow Cylinder, from Outside Diameter, Inside Diameter and Length)
Pipe Volume Calculator (Hollow Cylinder, from Outside Diameter, Inside Diameter and Length)
Free pipe and tube volume calculator. Enter the outside diameter, inside diameter and length to get the wall volume, the volume inside, and gallons.
Capsule Volume Calculator (V = πr²h + 4/3πr³)
Capsule Volume Calculator (V = πr²h + 4/3πr³)
Free capsule volume calculator. Enter the radius and the cylinder height to get V = πr²h + 4/3πr³ for a cylinder with hemisphere ends, in gallons and ft³.
Capsule Surface Area Calculator (S = 4πr² + 2πrh)
Capsule Surface Area Calculator (S = 4πr² + 2πrh)
Free capsule surface area calculator. Enter the radius and cylinder height to get S = 4πr² + 2πrh, the sphere and side areas, in² and ft², with a 3D view.

Date and time

Age Calculator (Exact Age in Years, Months and Days)
Age Calculator (Exact Age in Years, Months and Days)
Free age calculator. Get your exact age in years, months and days on any date, plus age in weeks, days and hours and the days to your next birthday.
Days Between Dates Calculator (Day Counter)
Days Between Dates Calculator (Day Counter)
Free day counter. Find the number of days between two dates, days until or since a date, with or without the end date, plus weeks, months and years.
Date Calculator (Add or Subtract Days, Weeks, Months and Years)
Date Calculator (Add or Subtract Days, Weeks, Months and Years)
Free date calculator: "What is 90 days from today?" Add or subtract days, weeks, months or years, or business days, and get the date and weekday.
Date and Time Calculator (Add or Subtract Hours, Minutes and Seconds)
Date and Time Calculator (Add or Subtract Hours, Minutes and Seconds)
Free calculator: "What time will it be 36 hours from now?" Add or subtract days, hours, minutes and seconds to a date and time, with the weekday.
Day of the Week Calculator (What Day Was It?)
Day of the Week Calculator (What Day Was It?)
Free day of the week calculator: "What day was I born?" Find the weekday of any date from year 1 to 9999, plus the day of the year and more.
Time Calculator (Add and Subtract Days, Hours, Minutes and Seconds)
Time Calculator (Add and Subtract Days, Hours, Minutes and Seconds)
Free time calculator. Add and subtract two times in days, hours, minutes and seconds, with the sum and difference shown at once and steps in seconds.
Time Zone Converter (Time Difference Calculator)
Time Zone Converter (Time Difference Calculator)
Free time zone converter. Enter a date, time and two time zones to get the local date, day of the week and time difference, with UTC offsets explained.
Work Hours Calculator (Hours Between Two Times, Minus Breaks)
Work Hours Calculator (Hours Between Two Times, Minus Breaks)
Free work hours calculator. Enter start and end times and a break to get hours worked, decimal hours for payroll (such as 7.5) and overnight shifts.
Time Duration Calculator (Elapsed Time Between Two Times or Dates)
Time Duration Calculator (Elapsed Time Between Two Times or Dates)
Free time duration calculator. Find the hours, minutes and seconds between two times, even across dates, with total hours, minutes and seconds.
Time Card Calculator (Weekly Hours Worked and Estimated Pay)
Time Card Calculator (Weekly Hours Worked and Estimated Pay)
Free time card calculator. Enter clock-in, clock-out and break times for each day to get daily hours, the weekly total in decimal hours and estimated pay.

Finance and economics

Compound Interest Calculator (Final Amount and Rate Conversion)
Compound Interest Calculator (Final Amount and Rate Conversion)
Free compound interest calculator. Get the final amount and interest, compare with simple interest on a graph, and convert APR to APY. Rule of 72 too.
Simple Interest Calculator (Interest, Principal, Rate and Time)
Simple Interest Calculator (Interest, Principal, Rate and Time)
Free simple interest calculator. Find interest and the total from principal, rate and time, or solve for any one of them. Yearly table and graph.
Interest Calculator (Savings Growth with Regular Contributions)
Interest Calculator (Savings Growth with Regular Contributions)
Free interest calculator. See how savings grow with compound interest and monthly or yearly deposits, after tax and inflation. Charts and formulas.
TVM Calculator (Time Value of Money Finance Calculator)
TVM Calculator (Time Value of Money Finance Calculator)
Free online TVM calculator that works like a BA II Plus. Enter four of N, I/Y, PV, PMT and FV to solve the fifth. Begin/end mode, P/Y, C/Y and schedule.
Present Value Calculator (Discounting and Present Value of an Annuity)
Present Value Calculator (Discounting and Present Value of an Annuity)
Free present value calculator: what is future money worth today? Discount a lump sum or find the present value of an annuity (begin or end), with a graph.
Future Value Calculator (Compound Growth with Regular Deposits)
Future Value Calculator (Compound Growth with Regular Deposits)
Free future value calculator: how much will a starting amount plus regular deposits grow to with compound interest? Breakdown, table and graph included.
ROI Calculator (Return on Investment and Annualized ROI)
ROI Calculator (Return on Investment and Annualized ROI)
Free ROI calculator. Find return on investment, gain or loss and annualized ROI from the amount invested and returned. Set the period by dates or years.
IRR Calculator (Internal Rate of Return from Cash Flows)
IRR Calculator (Internal Rate of Return from Cash Flows)
Free IRR calculator. Find the internal rate of return from an initial investment and yearly cash flows, with total return and an NPV graph showing the IRR.
Payback Period Calculator (Simple and Discounted Payback)
Payback Period Calculator (Simple and Discounted Payback)
Free payback period calculator. Find how many years it takes to earn back an investment, plus discounted payback and IRR, for even or uneven cash flows.
Average Return Calculator (Annualized Geometric Average and Cumulative Return)
Average Return Calculator (Annualized Geometric Average and Cumulative Return)
Free average return calculator. Turn returns for uneven periods (years and months) into the cumulative return and the annualized geometric average return.
GDP Calculator (Gross Domestic Product, Expenditure and Income Approach)
GDP Calculator (Gross Domestic Product, Expenditure and Income Approach)
Free GDP calculator. Find gross domestic product with the expenditure approach, C + I + G + (X − M), or the income approach, with a bar chart of each part.

Web marketing and ad metric

CTR Calculator (Click-Through Rate from Impressions and Clicks, Impressions Needed)
CTR Calculator (Click-Through Rate from Impressions and Clicks, Impressions Needed)
Free CTR calculator. Enter two of impressions, clicks and click-through rate to get the third, or find the impressions needed for a target click count.
Conversion Rate Calculator (CVR, Visitors Needed and Expected Conversions)
Conversion Rate Calculator (CVR, Visitors Needed and Expected Conversions)
Free conversion rate calculator. Enter two of visits, conversions and CVR to get the third, or find the visits needed for a target number of conversions.
CPC, CPM and CPA Calculator (Ad Cost Metrics and Budget from Target CPA)
CPC, CPM and CPA Calculator (Ad Cost Metrics and Budget from Target CPA)
Free CPC, CPM and CPA calculator. Get cost per click, cost per 1,000 impressions, cost per acquisition, CTR and CVR, or max CPC and budget from target CPA.
ROAS Calculator (Return on Ad Spend and Break-Even ROAS)
ROAS Calculator (Return on Ad Spend and Break-Even ROAS)
Free ROAS calculator. Enter two of revenue, ad spend and ROAS to get the third. Add gross margin for break-even ROAS, profit and ROI.
Break-Even CPA and Target CPA Calculator (Max Ad Spend per Conversion and Max CPC)
Break-Even CPA and Target CPA Calculator (Max Ad Spend per Conversion and Max CPC)
Free break-even CPA calculator. Enter order value and gross margin to get the max ad spend per conversion, plus target CPA and max CPC.
Customer Lifetime Value (LTV) Calculator for E-Commerce and Subscriptions
Customer Lifetime Value (LTV) Calculator for E-Commerce and Subscriptions
Free customer lifetime value calculator for stores (order value × frequency × years) and subscriptions (ARPU × gross margin ÷ churn), with a graph.
Customer Acquisition Cost (CAC) Calculator with LTV:CAC Ratio and Payback Period
Customer Acquisition Cost (CAC) Calculator with LTV:CAC Ratio and Payback Period
Free CAC calculator. Get blended and paid customer acquisition cost, the LTV:CAC ratio and CAC payback period, or work back to max CAC.
Churn Rate Calculator (Monthly and Annual Churn, Retention and Customer Lifetime)
Churn Rate Calculator (Monthly and Annual Churn, Retention and Customer Lifetime)
Free churn rate calculator. Get monthly churn, retention, average customer lifetime and annual churn, and customers left after n months.
A/B Test Significance Calculator (Conversion Rates, P-Value and Confidence Interval)
A/B Test Significance Calculator (Conversion Rates, P-Value and Confidence Interval)
Free A/B test significance calculator. Enter visitors and conversions for A and B to get conversion rates, lift, z-test p-value and a confidence interval.
A/B Test Sample Size Calculator (MDE, Significance, Power and Test Duration)
A/B Test Sample Size Calculator (MDE, Significance, Power and Test Duration)
Free A/B test sample size calculator. Get visitors per group and test duration from baseline CVR, MDE, significance and power, or solve for power.
SEO Traffic Estimator from CTR by Ranking Position (Monthly Traffic from Search Volume, Gain from Ranking Higher)
SEO Traffic Estimator from CTR by Ranking Position (Monthly Traffic from Search Volume, Gain from Ranking Higher)
Free SEO traffic estimator: monthly clicks from search volume and ranking position via a CTR curve, the gain from ranking higher, and the rank you need.
Break-Even Point Calculator (Break-Even Sales and Units, Margin of Safety, Sales for a Target Profit)
Break-Even Point Calculator (Break-Even Sales and Units, Margin of Safety, Sales for a Target Profit)
Free break-even calculator. Enter fixed costs, price and variable cost to get the contribution margin ratio, break-even sales and units, and a chart.
Markup vs. Margin Calculator (Cost, Selling Price, Markup %, Margin % and Cost Ratio)
Markup vs. Margin Calculator (Cost, Selling Price, Markup %, Margin % and Cost Ratio)
Free markup vs. margin calculator: enter any two of cost, price, markup %, margin % and cost ratio to get the rest, with conversion formulas and tables.
CAGR Calculator (Compound Annual Growth Rate, Solve for Any Value)
CAGR Calculator (Compound Annual Growth Rate, Solve for Any Value)
Free CAGR calculator. Enter any three of starting value, ending value, years and CAGR to find the fourth, with a year-by-year table and growth chart.

Health and fitness

BMI Calculator (Body Mass Index and Healthy Weight Range)
BMI Calculator (Body Mass Index and Healthy Weight Range)
Free BMI calculator for adults. Enter height and weight in ft, in and lb (or metric) to get your BMI, weight category and healthy weight range.
Sleep Cycle Calculator (Bedtime and Wake-Up Time)
Sleep Cycle Calculator (Bedtime and Wake-Up Time)
Free sleep calculator. Find what time to go to bed to wake up at the end of a 90-minute sleep cycle, or when to wake up if you go to bed now.
Calorie Calculator (Maintenance Calories and Weight Loss or Gain Plans)
Calorie Calculator (Maintenance Calories and Weight Loss or Gain Plans)
Free calorie calculator. Enter age, sex, height, weight and activity level to estimate maintenance calories, BMR and daily targets to lose or gain weight.
BMR Calculator (Basal Metabolic Rate and Daily Calories by Activity Level)
BMR Calculator (Basal Metabolic Rate and Daily Calories by Activity Level)
Free BMR calculator. Enter age, sex, height and weight to estimate your basal metabolic rate and daily calories burned at 6 activity levels. 3 formulas.
TDEE Calculator (Total Daily Energy Expenditure and How to Choose Your Activity Level)
TDEE Calculator (Total Daily Energy Expenditure and How to Choose Your Activity Level)
Free TDEE calculator. Estimate total daily energy expenditure from age, sex, height, weight and activity level, plus a guide to choosing an activity level.
Ideal Weight Calculator (Devine, Robinson, Miller and Hamwi Formulas)
Ideal Weight Calculator (Devine, Robinson, Miller and Hamwi Formulas)
Free ideal weight calculator. Enter height and sex to get ideal body weight by the Devine, Robinson, Miller and Hamwi formulas, plus a healthy BMI range.
Body Fat Calculator (Estimate with a Tape Measure, No Scale Needed)
Body Fat Calculator (Estimate with a Tape Measure, No Scale Needed)
Free body fat calculator. Measure your neck, waist (and hips for women) and height with a tape measure to estimate body fat %, fat mass and lean mass.
Lean Body Mass Calculator (LBM from Height and Weight with Three Formulas)
Lean Body Mass Calculator (LBM from Height and Weight with Three Formulas)
Free lean body mass calculator. Estimate LBM from height and weight with the Boer, James and Hume formulas, plus the Peters formula for children.
Calories Burned Calculator (Walking, Running, Chores and More with METs)
Calories Burned Calculator (Walking, Running, Chores and More with METs)
Free calories burned calculator. Pick from 44 activities like walking, running, swimming, lifting and chores, enter time and weight, and get kcal by METs.
Protein Calculator (How Much Protein Do I Need per Day?)
Protein Calculator (How Much Protein Do I Need per Day?)
Free protein calculator. Find how much protein you need per day with the US RDA (0.8 g/kg) and AMDR (10–35% of calories), plus a guide for exercise.
Macro Calculator (Daily Protein, Fat and Carbs)
Macro Calculator (Daily Protein, Fat and Carbs)
Free macro calculator. Get your daily calories and grams of protein, fat and carbs for 4 diet plans, with US AMDR ranges and limits for sat fat and sugar.
Carb Calculator (How Many Carbs Should I Eat a Day?)
Carb Calculator (How Many Carbs Should I Eat a Day?)
Free carb calculator. Find your daily grams of carbohydrate for weight loss, maintenance or gain at 40–65% of calories, with the US AMDR (45–65%).
Fat Intake Calculator (Daily Fat and Saturated Fat)
Fat Intake Calculator (Daily Fat and Saturated Fat)
Free fat intake calculator. Find your daily grams of fat (20–35% of calories) and your saturated fat limit (under 10%) to lose, keep or gain weight.
Child Height Predictor (Adult Height Estimate from Parents' Heights)
Child Height Predictor (Adult Height Estimate from Parents' Heights)
Free child height predictor. Enter both parents' heights to estimate your child's adult height (mid-parental target height) and its usual range.

Sports

Golf Handicap Calculator (Course Handicap and Handicap Index)
Golf Handicap Calculator (Course Handicap and Handicap Index)
Free golf handicap calculator. Find your Course Handicap from Slope and Course Rating, or your WHS Handicap Index from 3 to 20 score differentials.
Running Pace Calculator (Pace per Mile and per km from Distance and Time)
Running Pace Calculator (Pace per Mile and per km from Distance and Time)
Free running pace calculator. Enter distance and time to get pace per mile and per km, mph and split times for a 5K, 10K, half marathon and marathon.
One Rep Max Calculator (Estimate Your 1RM for Bench Press, Squat and More from Reps)
One Rep Max Calculator (Estimate Your 1RM for Bench Press, Squat and More from Reps)
Free one rep max calculator. Enter the weight and reps you lifted to estimate your 1RM with the Epley, Brzycki and Lombardi formulas, plus a %1RM chart.
Target Heart Rate Calculator (Heart Rate Zones, Karvonen Formula)
Target Heart Rate Calculator (Heart Rate Zones, Karvonen Formula)
Free target heart rate calculator. Get your exercise heart rate zones from your age (220 − age), or by the Karvonen formula with your resting heart rate.

Weather

Heat Index Calculator (Feels-Like Temperature from Temperature and Humidity)
Heat Index Calculator (Feels-Like Temperature from Temperature and Humidity)
Free heat index calculator. Enter the temperature and humidity (or dew point) to get the NWS feels-like temperature in °F and °C with its risk level.
Wind Chill Calculator (Winter Feels-Like Temperature from Wind Speed)
Wind Chill Calculator (Winter Feels-Like Temperature from Wind Speed)
Free wind chill calculator. Enter the temperature and wind speed to get the NWS wind chill in °F and °C. Supports mph, km/h, m/s and knots.
Dew Point Calculator (Temperature, Relative Humidity and Dew Point)
Dew Point Calculator (Temperature, Relative Humidity and Dew Point)
Free dew point calculator. Enter any two of temperature, relative humidity and dew point to get the third, in °F, °C or K, with vapor pressure.

Computer

Number Base Converter (Binary, Octal, Decimal and Hexadecimal)
Number Base Converter (Binary, Octal, Decimal and Hexadecimal)
Free number base converter. Convert between binary, octal, decimal and hexadecimal, with step-by-step place value and division steps.
IP Subnet Calculator (IPv4 and IPv6 CIDR)
IP Subnet Calculator (IPv4 and IPv6 CIDR)
Free IP subnet calculator. Get the network address, broadcast address, usable host range, subnet mask and wildcard mask from any CIDR. IPv6 too.
Bandwidth and Download Time Calculator (Internet Speed, Data Size and Unit Conversion)
Bandwidth and Download Time Calculator (Internet Speed, Data Size and Unit Conversion)
Free download time calculator. Find how long a file takes at your internet speed (Mbps), convert bits and bytes, and estimate website bandwidth.

Household energy and budget

Electricity Cost Calculator (Appliance Energy Use and Cost)
Electricity Cost Calculator (Appliance Energy Use and Cost)
Free electricity cost calculator. Enter watts, hours of use and your rate per kWh to get daily, weekly, monthly and yearly kWh and cost.
Electric Bill Calculator (kWh to Cost and Back)
Electric Bill Calculator (kWh to Cost and Back)
Free electric bill calculator. Turn the kWh on your bill into dollars with flat or tiered rates and a customer charge, or find the kWh a budget allows.
Annual kWh to Cost Calculator (EnergyGuide Label)
Annual kWh to Cost Calculator (EnergyGuide Label)
Free calculator that turns the yearly kWh on an EnergyGuide label into yearly, monthly and daily cost at your rate, and compares two models.
Air Conditioner Size Calculator (BTU per Square Foot)
Air Conditioner Size Calculator (BTU per Square Foot)
Free AC size calculator: find the BTU/h you need from square feet, ceiling height, sun and kitchen, or the room size an AC can cool. Chart and formulas.
Air Conditioner Running Cost Calculator (Cooling, Heating and Yearly Cost from kWh)
Air Conditioner Running Cost Calculator (Cooling, Heating and Yearly Cost from kWh)
Free AC running cost calculator: turn seasonal kWh and your electric rate into cooling, heating, monthly and yearly costs, and thermostat savings.
Heating Cost Comparison Calculator (Heat Pump, Space Heater, Electric Blanket)
Heating Cost Comparison Calculator (Heat Pump, Space Heater, Electric Blanket)
Free heating cost calculator: compare the hourly, daily and monthly cost of a heat pump, space heaters and electric blankets, and the cost per kWh of heat.
Gas vs Electric Cost Calculator (Cost per Unit of Heat for Water Heating, Cooking and Heating)
Gas vs Electric Cost Calculator (Cost per Unit of Heat for Water Heating, Cooking and Heating)
Free gas vs electric calculator: compare the cost of heat from natural gas or propane and electricity, with water heating cost and break-even gas price.
LED Savings Calculator (Yearly Savings and Payback from Switching to LED)
LED Savings Calculator (Yearly Savings and Payback from Switching to LED)
Free LED savings calculator. Find the yearly kWh and dollars saved by switching bulbs to LED, the payback period and the total savings over its life.
Salary Calculator (Hourly, Daily, Weekly, Monthly and Annual Pay)
Salary Calculator (Hourly, Daily, Weekly, Monthly and Annual Pay)
Free salary calculator. Convert pay between hourly, daily, weekly, monthly and annual, unadjusted and adjusted for holidays and vacation days.
Monthly Budget Calculator (Income, Expenses and Housing Ratio)
Monthly Budget Calculator (Income, Expenses and Housing Ratio)
Free budget calculator: enter monthly or yearly income and expenses to see take-home pay, surplus or deficit, a spending pie chart and your housing ratio.

Car

Gas Cost Calculator (Trip Fuel Cost from Distance, MPG and Gas Price)
Gas Cost Calculator (Trip Fuel Cost from Distance, MPG and Gas Price)
Free gas cost calculator. Enter trip distance, fuel economy (mpg) and gas price to get the gallons needed and the fuel cost, plus a cost table by mpg.
EV Charging Cost Calculator (Home and DC Fast Charging, Cost per Mile)
EV Charging Cost Calculator (Home and DC Fast Charging, Cost per Mile)
Free EV charging cost calculator. Enter battery size, charge level, charging loss and electricity rate to get the cost to charge and the cost per mile.
EV vs Gas Car Fuel Cost Calculator (Cost per Mile, Yearly Savings and Payback Years)
EV vs Gas Car Fuel Cost Calculator (Cost per Mile, Yearly Savings and Payback Years)
Free EV vs gas car calculator. Enter miles, mpg, gas price, EV efficiency and electricity rate to compare fuel costs per mile and per year, plus payback.
Gas Mileage Calculator (Real-World MPG from a Fill-Up)
Gas Mileage Calculator (Real-World MPG from a Fill-Up)
Free gas mileage (MPG) calculator. Enter two odometer readings and the gallons at your fill-up to get your real-world mpg and cost per mile.
Tire Size Calculator (Diameter, Sidewall, Plus Sizing and Speedometer Error)
Tire Size Calculator (Diameter, Sidewall, Plus Sizing and Speedometer Error)
Free tire size calculator. Enter a size like P265/70R17 to get the diameter in inches and sidewall height, compare two tires and check speedometer error.

Solar power and battery

Solar Panel Output Calculator (Monthly and Annual kWh from System Size, Peak Sun Hours, Direction and Tilt)
Solar Panel Output Calculator (Monthly and Annual kWh from System Size, Peak Sun Hours, Direction and Tilt)
Free solar output calculator. Estimate monthly and yearly kWh from system size (kW), peak sun hours, roof direction and tilt, with US city presets.
Solar Panel Calculator (How Many Panels and How Much Roof Space from System Size, Yearly kWh or Roof Area)
Solar Panel Calculator (How Many Panels and How Much Roof Space from System Size, Yearly kWh or Roof Area)
Free solar panel calculator. Find how many panels you need for a system size or yearly kWh, how many fit on your roof, and the roof area needed.
Solar Payback Calculator (Bill Savings, Export Credits, Degradation and Break-Even Year)
Solar Payback Calculator (Bill Savings, Export Credits, Degradation and Break-Even Year)
Free solar payback calculator. Find the yearly savings, simple payback and break-even year from system cost, kWh, self-use share and your rates.
Home Battery Size Calculator (Backup Hours and kWh Needed for Outages and Nighttime Use)
Home Battery Size Calculator (Backup Hours and kWh Needed for Outages and Nighttime Use)
Free home battery calculator. Find the battery size (kWh) you need for an outage or nighttime use, and how many hours a battery can run your devices.

Home and DIY

Tile Calculator (How Many Tiles, Boxes and Cost)
Tile Calculator (How Many Tiles, Boxes and Cost)
Free tile calculator. Enter the tile size, grout width and floor or wall area to get how many tiles and boxes you need, with 5-10% for waste, and the cost.
Stair Calculator (Rise, Run, Number of Steps, Stringer Length and Angle)
Stair Calculator (Rise, Run, Number of Steps, Stringer Length and Angle)
Free stair calculator: get riser height, number of steps, total run, stringer length and angle from the total rise, with IRC code and headroom checks.
Concrete Calculator (Cubic Yards, Weight and Bags)
Concrete Calculator (Cubic Yards, Weight and Bags)
Free concrete calculator for slabs, footings, post holes, curbs and steps. Get cubic yards, weight and how many 80, 60 or 40 lb bags, with 5-10% extra.
Wall Area Calculator (Wall, Ceiling and Floor Square Footage, with Doors, Windows, Perimeter and Volume)
Wall Area Calculator (Wall, Ceiling and Floor Square Footage, with Doors, Windows, Perimeter and Volume)
Free room area calculator. Enter length, width, ceiling height, doors and windows to get floor, ceiling and net wall square footage, perimeter and volume.
Wallpaper Calculator (How Many Rolls, with Pattern Repeat and Waste)
Wallpaper Calculator (How Many Rolls, with Pattern Repeat and Waste)
Free wallpaper calculator. From room size, ceiling height, doors and windows, get the strips, length and double rolls needed, with repeat and waste.
Paint Calculator (How Many Gallons and Cans, from Area, Coverage and Coats)
Paint Calculator (How Many Gallons and Cans, from Area, Coverage and Coats)
Free paint calculator. From the area, coverage per gallon, coats and waste, get the gallons and cans you need and the cost, or the area paint will cover.
Flooring Calculator (Planks, Boxes, Waste Factor and Cost)
Flooring Calculator (Planks, Boxes, Waste Factor and Cost)
Free flooring calculator. Enter the room and plank size to get the planks and boxes you need with a waste factor, the area covered and the cost.
Exterior Wall Area Calculator (Square Footage for Painting and Siding)
Exterior Wall Area Calculator (Square Footage for Painting and Siding)
Free calculator for the exterior wall area to paint or side. Use perimeter × wall height minus windows and doors, add gables, or estimate from floor area.
Gravel Calculator (Cubic Yards, Tons and Bags)
Gravel Calculator (Cubic Yards, Tons and Bags)
Free gravel calculator. Find how much gravel, crushed stone, sand or soil you need in ft³, cubic yards, pounds, tons and bags from area and depth.
Mortar and Concrete Mix Calculator (Cement, Sand, Gravel, Water and Bags)
Mortar and Concrete Mix Calculator (Cement, Sand, Gravel, Water and Bags)
Free mix calculator. From a mix ratio (1:3 mortar, 1:2:4 concrete) and the volume, find the cement, sand, gravel and water, and the bags you need.
Grade and Slope Calculator (Percent, Degrees, Roof Pitch and Ratio, with Lengths)
Grade and Slope Calculator (Percent, Degrees, Roof Pitch and Ratio, with Lengths)
Free grade calculator. Convert a slope between percent, degrees, roof pitch (x/12), ratio (1/n) and rise over run, and find the rise, run and slope length.
Lumber Cut List Calculator (Boards Needed and Cutting Layout)
Lumber Cut List Calculator (Boards Needed and Cutting Layout)
Free cut list calculator. Enter the board length, saw kerf and the parts you need to get the fewest boards, a cutting layout, offcuts and the cost.
Lot Coverage and Floor Area Ratio (FAR) Calculator (Maximum Buildable Area)
Lot Coverage and Floor Area Ratio (FAR) Calculator (Maximum Buildable Area)
Free lot coverage and floor area ratio (FAR) calculator. Get both ratios from your lot and building areas, or the maximum footprint and floor area allowed.
Sheet Vinyl and Carpet Roll Calculator (Length Needed, Seams, Offcuts and Cost)
Sheet Vinyl and Carpet Roll Calculator (Length Needed, Seams, Offcuts and Cost)
Free sheet vinyl and carpet roll calculator. Compare running the roll both ways to get the length to buy, seams, offcuts and cost, with a layout drawing.
Insulation Calculator (Area, Batts, Bags and R-Value)
Insulation Calculator (Area, Batts, Bags and R-Value)
Free insulation calculator. Enter the area and batt size to get the batts and bags you need with a waste factor, plus the R-value, volume and cost.
Curtain Size Calculator (Finished Width, Length and Fabric Yardage from Fullness)
Curtain Size Calculator (Finished Width, Length and Fabric Yardage from Fullness)
Free curtain size calculator. Get the finished width and length from your rod and window, then the fabric widths and yards to buy with fullness and hems.
TV Size and Viewing Distance Calculator (4K, Full HD and 8K)
TV Size and Viewing Distance Calculator (4K, Full HD and 8K)
Free TV size and viewing distance calculator. Get the right TV size for your seating distance, or the distance, screen size and viewing angle for a TV.
Soil Calculator for Beds, Planters and Pots (Cubic Feet, Cubic Yards, Pounds and Bags)
Soil Calculator for Beds, Planters and Pots (Cubic Feet, Cubic Yards, Pounds and Bags)
Free soil calculator for raised beds, gardens, planters and pots. Get the cubic feet, cubic yards, weight and bags of soil, mix or sand you need.
Sod Calculator (Square Feet, Pallets and Topdressing)
Sod Calculator (Square Feet, Pallets and Topdressing)
Free sod calculator. Find how many pallets and pieces of sod you need for your lawn, with waste, gaps and topdressing in ft³ and bags.
Concrete Block Calculator (Blocks, Mortar Bags and Rebar for a Block Wall)
Concrete Block Calculator (Blocks, Mortar Bags and Rebar for a Block Wall)
Free concrete block (CMU) calculator. Find how many blocks and bags of mortar a block wall needs, plus core grout and a rebar estimate.
Brick Calculator (Patios, Paths, Garden Edges and Low Walls)
Brick Calculator (Patios, Paths, Garden Edges and Low Walls)
Free brick calculator. Find how many bricks you need for a patio, path, garden edge or low wall, with waste, mortar and pallets.
Deck Materials Calculator (Decking, Joists, Posts and Screws)
Deck Materials Calculator (Decking, Joists, Posts and Screws)
Free deck materials calculator. Find how many deck boards, joists, beams and posts you need, plus screws and cost, with a framing plan.
Ramp Length Calculator (Rise and Slope, ADA 1:12)
Ramp Length Calculator (Rise and Slope, ADA 1:12)
Free ramp length calculator. Enter the rise and slope (1:12, % or degrees) to get the run and ramp length, or find the slope of the space you have.
Pilot Hole and Screw Length Calculator (#6, #8, #10 Wood Screws)
Pilot Hole and Screw Length Calculator (#6, #8, #10 Wood Screws)
Free pilot hole calculator. Find the pilot hole and nearest drill bit for #6, #8 and #10 screws in softwood or hardwood, and the right screw length.
Room Volume and Ventilation Calculator (Air Changes per Hour, CFM)
Room Volume and Ventilation Calculator (Air Changes per Hour, CFM)
Free room ventilation calculator. Find room volume, the CFM you need from air changes per hour, and the real ACH of your fan. Per-person check too.
Paint Thinning Calculator (Water or Thinner to Add, 2-Part Hardener)
Paint Thinning Calculator (Water or Thinner to Add, 2-Part Hardener)
Free paint thinning calculator: how much water or thinner to add for a thinning rate (%), paint needed for a batch, and 2-part hardener from a mix ratio.
Baseboard, Crown Molding and Trim Calculator (Linear Feet and Pieces)
Baseboard, Crown Molding and Trim Calculator (Linear Feet and Pieces)
Free baseboard and crown molding calculator. Get the linear feet with waste, how many 8, 12 or 16 ft pieces to buy, leftover and cost, minus doors.
Blind and Shade Size Calculator (Inside and Outside Mount)
Blind and Shade Size Calculator (Inside and Outside Mount)
Free blind size calculator for inside and outside mount. Get the order width and height for blinds, roller and cellular shades, to 1/8 in, plus cost.
Picture Hanging Height and Spacing Calculator (Nail Height, Gallery Wall)
Picture Hanging Height and Spacing Calculator (Nail Height, Gallery Wall)
Free picture hanging calculator. Find where to put the nail for a frame centered at 57 in, with a wire or D-rings, and the spacing for a row of frames.
Drain Slope and Pipe Fall Calculator (Inches per Foot, 1/n, Percent)
Drain Slope and Pipe Fall Calculator (Inches per Foot, 1/n, Percent)
Free drain slope calculator. Get the pipe fall from the run and slope (1/4 or 1/8 in per ft), the slope from the fall, invert depths, shower floor slope.
Screw Calculator (How Many Screws for Drywall, Plywood and Decking)
Screw Calculator (How Many Screws for Drywall, Plywood and Decking)
Free screw calculator for drywall, plywood and deck boards. From sheet size, stud spacing and screw spacing, get screws per sheet, total, boxes and cost.
Board Foot Calculator (Board Feet, Cubic Feet and Lumber Cost)
Board Foot Calculator (Board Feet, Cubic Feet and Lumber Cost)
Free board foot calculator. Enter thickness, width, length and pieces to get board feet, cubic feet and cost ($/bf or $/MBF), or the boards for a target.
Fence Calculator (Posts, Panels, Rails and Pickets)
Fence Calculator (Posts, Panels, Rails and Pickets)
Free fence calculator. From the side lengths, get the posts, panels, rails, pickets, post hole concrete and cost for vinyl, wood or chain link fences.
Wood Shrinkage Calculator (Wood Movement from Moisture Content Change)
Wood Shrinkage Calculator (Wood Movement from Moisture Content Change)
Free wood movement calculator. From width, grain (flatsawn or quartersawn), species and moisture change, get shrinkage or swelling and seasonal movement.
Caulk Calculator (How Many Tubes of Caulk and Sealant, and Adhesive by Coverage)
Caulk Calculator (How Many Tubes of Caulk and Sealant, and Adhesive by Coverage)
Free caulk calculator. From joint width, depth and length, get the fluid ounces and 10.1 oz tubes you need, or adhesive gallons from area and coverage.
Room Heat Loss Calculator (BTU per Hour from U-Factor, Area and Temperature Difference)
Room Heat Loss Calculator (BTU per Hour from U-Factor, Area and Temperature Difference)
Free room heat loss calculator. From each wall, window, ceiling and floor's area and U-factor, get BTU/h lost, where heat escapes, heating size and cost.
Furniture Fit Calculator (Through a Door, Around a Hallway Corner, Into an Elevator)
Furniture Fit Calculator (Through a Door, Around a Hallway Corner, Into an Elevator)
Free furniture fit calculator. Check if a couch or appliance fits through a door, around a hallway corner or into an elevator, tilted or not.
Moving Box Calculator (How Many Boxes Do I Need?)
Moving Box Calculator (How Many Boxes Do I Need?)
Free moving box calculator. Estimate how many small and medium boxes you need from your belongings or household size, plus tape, volume and cost.
Storage Capacity Calculator (Cubic Feet, How Many Books and Bins Fit)
Storage Capacity Calculator (Cubic Feet, How Many Books and Bins Fit)
Free storage capacity calculator. Find the cubic feet of a cabinet or closet, how many bins or books fit, the shelf width needed and closet rod space.
Plywood Cut Calculator (How Many Pieces from a Sheet, 2D Cutting Layout)
Plywood Cut Calculator (How Many Pieces from a Sheet, 2D Cutting Layout)
Free plywood cut calculator. Find how many 4x8 sheets you need for your parts, with kerf, grain direction, a cutting layout, offcuts, yield and cost.
Shelf Sag and Load Calculator (Deflection from Material, Thickness, Span and Load; Maximum Span, Load and Thickness)
Shelf Sag and Load Calculator (Deflection from Material, Thickness, Span and Load; Maximum Span, Load and Thickness)
Free shelf sag calculator. Find how much a bookshelf sags under a load, and work back to the maximum span, load or thickness for 1/8 in or L/300.