Logarithm Calculator (Log Calculator)

Of the three values in "y = log_a(x)" (base a, argument x and log value y), enter the two you know and press "Calculate". The one left blank is calculated. The equation below is linked to the fields, so you can also type the base, argument or log value right into it.

Argument x (inside the log)

Base a

Log value y

Leave the value you want to find blank (enter exactly two). Besides numbers, the base can be "e" for the natural logarithm (use 10 for the common logarithm). The argument must be greater than 0, and the base must be greater than 0 and not 1.

Result

Enter two values in the fields on the left and press "Calculate". The result will appear here.

[ CLOSE ]

What you can do on this page
What is this calculation used for?
How to Use
Formula
Symbols and terms
- Symbols
- Terms
Good to know before you start
How to calculate it in Excel
How to calculate it in Google Sheets
How to calculate it in Python
How to write it in LaTeX and other math languages (copy and paste)
How to have ChatGPT do the calculation
DataChef Features
Related Features
NumberChef Calculators List

What you can do on this page

For the logarithm \(y = \log_a x\), enter the two you know out of the base \(a\), the argument \(x\) and the log value \(y\), and the third appears on the spot
You can use any base. Enter "10" as the base for the common logarithm, or "e" for the natural logarithm (\(\ln\))
Besides log values like \(\log_2 8 = 3\), it also answers "what is 2 to the 10th power?" (solve for the argument, \(2^{10} = 1024\)) and "what number to the 4th power is 81?" (solve for the base)
A plain-language explanation of the formulas and copy-and-paste formulas for Excel, Google Sheets and Python are all on this page

A logarithm has two rules. The argument must be greater than 0 (the domain), and the base must be greater than 0 and not equal to 1 (the base restrictions). Input that breaks these rules gives an error.

What is this calculation used for?

What decibels (dB) really are (audio and noise)

The decibel, the unit of loudness, is defined with the common logarithm of a ratio of sound energies. Even when the energy becomes 100 times larger, the level rises by only \(10 \times \log_{10} 100 = 20\) dB.
Our ears sense sound by "how many times louder", so a logarithmic unit fits them perfectly. Safe listening levels for earbuds and workplace noise guidelines (NIOSH recommends no more than 8 hours a day at 85 dB) are all built on this logarithm formula.

Reading earthquake magnitudes correctly (disaster safety)

Magnitude is based on the logarithm of an earthquake's energy. One step up in magnitude releases about 32 times (\(10^{1.5}\) times) the energy, so a magnitude 7 earthquake has about 1000 times the energy of a magnitude 5.
Knowing logarithms lets you read this as "3 more digits of energy", not "only 2 more", and that directly shapes how you prepare for disasters.

pH (acidic or basic) is a logarithmic scale (science and daily life)

pH, which measures how acidic a solution is, is defined with the common logarithm of the hydrogen ion concentration (\(\mathrm{pH} = -\log_{10}[\mathrm{H}^+]\)). Between lemon juice at pH 2 and water at pH 7, the concentration differs not by "5" but by a factor of \(10^5\) (100,000).
Turning quantities that span many powers of ten into easy numbers from about 0 to 14 is what logarithms do best. The pH numbers on cleaners, pool test kits and garden soil tests all rely on it.

How many years it takes to double your money (compound interest and investing)

At 3% interest compounded yearly, your money doubles when \(1.03^y = 2\), so \(y = \log_{1.03} 2 \approx 23.4\) years (assuming the same return every year).
The well-known "rule of 72" (72 ÷ interest rate in % ≈ years to double) is actually an approximation of this logarithm. It is a solid base for long-term money plans such as college savings and retirement, with numbers instead of guesses.

Bits of data are set by logarithms (IT)

The number of bits needed to tell \(n\) different things apart is \(\log_2 n\). For example, 256 different values fit in \(\log_2 256 = 8\) bits (1 byte).
Password strength (roughly how many guesses a brute-force attack needs) is also measured as "how many bits", a logarithm. This calculation supports the whole digital world.

Musical intervals are logarithms of frequency (music)

Neighboring piano keys (a half step) all have the same frequency ratio, \(2^{1/12} \approx 1.0595\) (equal temperament). If the frequency ratio of two notes is \(r\), the number of half steps between them is \(12 \times \log_2 r\).
For the A at 440 Hz and the A at 880 Hz, that is \(12 \times \log_2 2 = 12\) half steps, exactly one octave. Instrument tuners and pitch shifting in music software run on this logarithm.

Formula

Definition of a logarithm (what \(y = \log_a x\) says)

Standard notation (the usual math form)

\(x\) \(=\) \(a\) \(y\)

In words (symbols replaced with words)

③ \(x\): argument \(=\) ① \(a\): base ② \(y\): log value

The formula in words

① Raise the \(a\): base

② to the power of the \(y\): log value

③ and you get the \(x\): argument . This "what power" number \(y\) is written as \(y = \log_a x\)

Quick example

Rewriting "2 to the 3rd power is 8" (2 × 2 × 2 = 8) as a logarithm gives

argument 8 \(=\) base 2 log value 3

\(2^{3} = 2 \times 2 \times 2 = 8\)

\(\log_{2} 8 = 3\)

Key idea

A logarithm undoes a power (an exponent). If "what is \(2^3\)?" has the answer 8, then "2 to what power is 8?" has the answer \(\log_2 8 = 3\). The same equation also finds the argument: if you know the base and the log value, the argument is \(x = a^y\). Any power of a positive number \(a\) is always positive, so the argument \(x\) must be greater than 0 (the domain of a logarithm). Also, any power of 1 is still 1, so 1 cannot be a base, and neither can 0 or a negative number (the base must be greater than 0 and not 1).

Finding the log value (change of base formula)

Standard notation (the usual math form)

\(\log_{a} x\) \(=\) \(\ln x\) \(\div\) \(\ln a\)

In words (symbols replaced with words)

③ \(\log_a x\): log value to find \(=\) ① \(\ln x\): natural log of the argument \(\div\) ② \(\ln a\): natural log of the base

The formula in words

① Take the \(\ln x\): natural log of the argument

② divide it by the \(\ln a\): natural log of the base

③ and you get the \(\log_a x\): log value to find

Quick example

The log of 8 with base 2 (2 to what power is 8) is

log value \(\log_2 8\) \(=\) natural log of 8 \(\ln 8\) \(\div\) natural log of 2 \(\ln 2\)

\(\log_{2} 8 = \ln 8 \div \ln 2 = 2.0794\cdots \div 0.6931\cdots = 3\)

Key idea

Calculators and programming languages usually offer only the natural logarithm \(\ln\) (base \(e\)) and the common logarithm \(\log_{10}\) (base 10). A logarithm with any base can be found as "log of the argument ÷ log of the base". This is the change of base formula, and this calculator uses it internally. Using the common logarithm instead of the natural logarithm gives the same answer (\(\log_a x = \log_{10} x \div \log_{10} a\)). The only rule is to use the same kind of logarithm on the top and the bottom.

Finding the base (from the argument and the log value)

Standard notation (the usual math form)

\(a\) \(=\) \(x\) \(1/y\)

In words (symbols replaced with words)

③ \(a\): base \(=\) ① \(x\): argument ② \(1/y\): 1 over the log value

The formula in words

① Raise the \(x\): argument

② to the power \(1/y\): 1 over the log value (that is, take the \(y\)th root)

③ and you get the \(a\): base

Quick example

"The number whose 4th power is 81" (the base when the argument is 81 and the log value is 4) is

\(a\): base \(=\) argument 81 one fourth

\(a = 81^{1/4} = \sqrt[4]{81} = 3\)

\(3 \times 3 \times 3 \times 3 = 81\)

Key idea

"Raising to the power \(\frac{1}{y}\)" is the same as "taking the \(y\)th root" (finding the number whose \(y\)th power is that number). This formula does not work when the log value is \(y = 0\) (any number to the power 0 is 1, so if the argument is 1 every base works and the base is not unique, and if the argument is not 1 there is no base), or when the argument is \(x = 1\) (the base would have to be 1, which is not allowed). This calculator gives an error in those cases.

Product rule (the log of a product is a sum)

Standard notation (the usual math form)

\(\log_{a} MN\) \(=\) \(\log_{a} M\) \(+\) \(\log_{a} N\)

In words (symbols replaced with words)

③ \(\log_a MN\): log of the product \(MN\) \(=\) ① \(\log_a M\): log of \(M\) \(+\) ② \(\log_a N\): log of \(N\)

The formula in words

① Add the \(\log_a M\): log of \(M\)

② and the \(\log_a N\): log of \(N\)

③ and you get the \(\log_a MN\): log of the product \(MN\)

Quick example

With base 10, the log of the product of 4 and 25 (4 × 25 = 100) is

log of the product 4 × 25 \(=\) log of 4 (about 0.6021) \(+\) log of 25 (about 1.3979)

\(\log_{10}(4 \times 25) = \log_{10} 4 + \log_{10} 25 \approx 0.6021 + 1.3979 = 2\)

\(\log_{10} 100 = 2\)

Key idea

Taking logarithms turns multiplication into addition. This is the most important property of logarithms. Before calculators, astronomers used tables of logarithms to turn the multiplication of huge numbers into addition. The slide rule works on the same principle.

Quotient rule (the log of a quotient is a difference)

Standard notation (the usual math form)

\(\log_{a} \dfrac{M}{N}\) \(=\) \(\log_{a} M\) \(-\) \(\log_{a} N\)

In words (symbols replaced with words)

③ \(\log_a \frac{M}{N}\): log of the quotient \(\frac{M}{N}\) \(=\) ① \(\log_a M\): log of \(M\) \(-\) ② \(\log_a N\): log of \(N\)

The formula in words

① From the \(\log_a M\): log of \(M\)

② subtract the \(\log_a N\): log of \(N\)

③ and you get the \(\log_a \frac{M}{N}\): log of the quotient \(\frac{M}{N}\)

Quick example

With base 10, the log of the quotient of 1000 divided by 10 (1000 ÷ 10 = 100) is

log of the quotient 1000 ÷ 10 \(=\) log of 1000 (3) \(-\) log of 10 (1)

\(\log_{10}\dfrac{1000}{10} = \log_{10} 1000 - \log_{10} 10 = 3 - 1 = 2\)

\(\log_{10} 100 = 2\)

Key idea

This is the "division version" of the product rule. For the same reason that multiplication turns into addition, division turns into subtraction. It is easy to remember as the exponent rule \(a^{m} \div a^{n} = a^{m-n}\) restated in the language of logarithms.

Power rule (the exponent moves to the front)

Standard notation (the usual math form)

\(\log_{a} M^{k}\) \(=\) \(k\) \(\times\) \(\log_{a} M\)

In words (symbols replaced with words)

③ \(\log_a M^k\): log of the power \(M^k\) \(=\) ① \(k\): exponent \(\times\) ② \(\log_a M\): log of \(M\)

The formula in words

① Multiply the \(k\): exponent

② by the \(\log_a M\): log of \(M\)

③ and you get the \(\log_a M^k\): log of the power \(M^k\)

Quick example

With base 10, the log of 2 to the 10th power (\(2^{10} = 1024\)) is

log of \(2^{10}\) \(=\) exponent 10 \(\times\) log of 2 (about 0.3010)

\(\log_{10} 2^{10} = 10 \times \log_{10} 2 \approx 10 \times 0.3010 = 3.010\)

\(\log_{10} 1024 \approx 3.010\)

Key idea

The log of a power (multiplying \(k\) times) turns into a single multiplication: \(k\) times the log. In this example, \(\log_{10} 2^{10} \approx 3.010\) tells you that "\(2^{10}\) is about \(10^{3.010}\) in size", which fits perfectly with \(2^{10} = 1024\) having 4 digits (the whole-number part of the common logarithm plus 1 is the number of digits). Questions like "how many digits does \(2^{100}\) have?" are solved with this rule.

The logarithm \(y = \log_a x\) is the number that tells "the base \(a\) to what power gives the argument \(x\)". It is exactly the reverse of a power. With the change of base formula, a logarithm with any base can be calculated from the natural logarithm \(\ln\) or the common logarithm \(\log_{10}\).

Symbols and terms

Symbols

\(\log_a x\)	log base a of x	"The logarithm of \(x\) with base \(a\)". The number that tells what power of the base \(a\) gives the argument \(x\). (Example - \(\log_2 8 = 3\))
\(a\)	a (the base)	The number the logarithm is built on, written small below the line in \(\log_a x\). It must be greater than 0 and not 1.
\(x\)	x (the argument)	The number inside the log. It must be greater than 0 (the domain).
\(y\)	y (the log value)	The result of the logarithm. It is the exponent itself: "the base to the power \(y\) gives the argument".
\(\log_{10} x\)	log base 10 of x (common log)	The logarithm with base 10. It is tied directly to the number of digits (\(\log_{10} 1000 = 3\)) and is widely used in science and engineering. Often the base is left out and it is written \(\log x\).
\(\ln x\)	natural log of x	The logarithm with base \(e\) (Euler's number). It works best with calculus and is standard in math, physics and finance.
\(e\)	e (Euler's number)	A special number, about 2.71828…, whose digits go on forever. It is the base of the natural logarithm. On this calculator, enter "e" in the base field to use it.
\(M,\ N\)	M, N	Arguments used to explain the log rules (product, quotient and power). Both are greater than 0.
\(\sqrt[n]{x}\)	the nth root of x	The number whose \(n\)th power is \(x\). It is the same as \(x^{1/n}\) (the power 1 over \(n\)). (Example - \(\sqrt[4]{81} = 3\))

Terms

logarithm (log)	The number that tells what power of the base gives the argument. It is the reverse of a power and is taught in Algebra 2. The symbol log is short for logarithm.
base	The number the logarithm is built on. In \(\log_2 8\), the base is 2. Only numbers greater than 0 and not equal to 1 can be a base.
argument	The number inside the log. In \(\log_2 8\), the argument is 8. Only numbers greater than 0 can be an argument.
domain	The set of numbers a logarithm accepts. The argument must be greater than 0, because any power of a positive number is always positive, so there is no log of 0 or of a negative number. It is the first thing to check when you solve equations or inequalities with logarithms.
base restrictions	The rule that the base must be greater than 0 and not equal to 1. Any power of 1 is still 1, so the logarithm would not be defined, and powers of 0 or of a negative number are not defined for every exponent.
common logarithm (common log)	The logarithm with base 10. It is tied directly to the number of digits, and most logarithms in everyday life, such as pH, decibels and earthquake magnitude, are common logarithms.
natural logarithm (natural log)	The logarithm with base \(e\) (about 2.718). Its symbol is \(\ln\). It is the easiest logarithm to use in calculus and is used for interest calculations and for studying natural processes.
Euler's number	The number \(e = 2.71828\ldots\), whose digits go on forever. It appears naturally whenever there is continuous growth. Like \(\pi\), it is a famous irrational number.
power	Multiplying the same number by itself several times. As in \(2^3 = 2 \times 2 \times 2\), the small number at the upper right (the exponent) tells how many times. A logarithm is the reverse of a power.
exponent	The small number at the upper right of a power that tells what power to raise to. In \(2^3\), the exponent is 3. A log value is the exponent you are looking for.
change of base formula	The formula that rewrites a logarithm with any base as "log of the argument ÷ log of the base". Even if a calculator or program has only \(\ln\) and \(\log_{10}\), this formula lets you calculate a logarithm with any base.
root (nth root)	The number whose \(n\)th power is the given number. As in "the number whose 4th power is 81 is 3", solving for the base is finding this root.

Good to know before you start

Here is what helps you use the calculation on this page with real understanding, not just by pressing the button.
If you get stuck, going back to these topics is the fastest way forward.

Powers and exponents (Grade 6)	Knowing that the small number at the upper right (the exponent) is "how many times to multiply", as in \(2^3 = 2 \times 2 \times 2 = 8\)
Extending exponents (Grade 8 and Algebra 2)	Knowing that exponents extend to 0 and negative numbers, as in \(a^0 = 1\) and \(a^{-n} = \frac{1}{a^n}\) Knowing that \(a^{1/n}\) (the power 1 over \(n\)) is the same as taking the \(n\)th root
Square roots and nth roots (Grade 8 to Algebra 2)	Being able to answer a power question in reverse, such as "the positive number whose square is 9 is 3"
The idea of inverse operations (elementary and middle school)	Seeing that a logarithm undoes a power, just as division undoes multiplication

How to calculate it in Excel

Copy the whole table below and paste it into cell A1 in Excel. It works as is.

Table to find the log value y

Argument x	100
Base a	10
Log value y	=LOG(B1,B2)

Table to find the argument x

Base a	2
Log value y	10
Argument x	=B1^B2

Table to find the base a

Argument x	81
Log value y	4
Base a	=B1^(1/B2)

Table to check the product rule

Argument M	4
Argument N	25
log M + log N (base 10)	=LOG(B1,10)+LOG(B2,10)
log of the product M×N (base 10)	=LOG(B1*B2,10)

Table to check the quotient rule

Argument M	1000
Argument N	10
log M − log N (base 10)	=LOG(B1,10)-LOG(B2,10)
log of the quotient M÷N (base 10)	=LOG(B1/B2,10)

Table to check the power rule

Argument M	2
Exponent k	10
k × (log M) (base 10)	=B2*LOG(B1,10)
log of the power M^k (base 10)	=LOG(B1^B2,10)

After pasting, the upper rows are your inputs, and the last rows (the green formulas) show the results calculated automatically.
The Excel LOG function is written as "=LOG(number, base)" (if you leave out the base, it uses the common logarithm, base 10). The natural logarithm (base e) is "=LN(number)".
In the first table, for example, B3 shows 2 (because 10 to the 2nd power is 100). To calculate a natural logarithm, change B3 in the first table to "=LN(B1)".
The fourth to sixth tables check the log rules. The two formulas at the bottom always give the same value.

How to calculate it in Google Sheets

Copy the whole table below and paste it into cell A1 in Google Sheets. It works as is.

Table to find the log value y

Argument x	100
Base a	10
Log value y	=LOG(B1,B2)

Table to find the argument x

Base a	2
Log value y	10
Argument x	=B1^B2

Table to find the base a

Argument x	81
Log value y	4
Base a	=B1^(1/B2)

Table to check the product rule

Argument M	4
Argument N	25
log M + log N (base 10)	=LOG(B1,10)+LOG(B2,10)
log of the product M×N (base 10)	=LOG(B1*B2,10)

Table to check the quotient rule

Argument M	1000
Argument N	10
log M − log N (base 10)	=LOG(B1,10)-LOG(B2,10)
log of the quotient M÷N (base 10)	=LOG(B1/B2,10)

Table to check the power rule

Argument M	2
Exponent k	10
k × (log M) (base 10)	=B2*LOG(B1,10)
log of the power M^k (base 10)	=LOG(B1^B2,10)

Google Sheets has the same LOG and LN functions as Excel, so exactly the same formulas work.
Copy the whole table, paste it into cell A1, and replace the input numbers with your own.

How to calculate it in Python

import math

x = 100   # argument (a number greater than 0)
a = 10    # base (greater than 0 and not 1; use math.e for the natural log)

y = math.log(x, a)   # log value y = log_a(x)
print(f"Log of {x} with base {a}: {y}")

# The common log (base 10) and natural log (base e) also have their own functions
print(f"Common log log10({x}) = {math.log10(x)}")
print(f"Natural log ln({x}) = {math.log(x)}")

# You can also work backward
true_number = a ** y        # find the argument (raise the base to the power y)
base_number = x ** (1 / y)  # find the base (raise the argument to the power 1/y)
print(f"Argument: {true_number}, base: {base_number}")

Runs with only the math module from the standard library. math.log(argument, base) gives the log value (if you leave out the base, it gives the natural logarithm). Change x and a at the top to your own numbers and run it.

How to write it in LaTeX and other math languages (copy and paste)

Definition of a logarithm (what \(y = \log_a x\) says)

y = logₐ x ⇔ x = aʸ

y = \log_{a} x \iff x = a^{y}

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <mi>y</mi>
    <mo>=</mo>
    <msub><mi>log</mi><mi>a</mi></msub>
    <mi>x</mi>
    <mo>&#x21D4;</mo>
    <mi>x</mi>
    <mo>=</mo>
    <msup><mi>a</mi><mi>y</mi></msup>
  </mrow>
</math>

y = log_a x iff x = a^y

Log[a, x]

y := log[a](x);

y = log(x)/log(a);

y = log_a(x)

Finding the log value (change of base formula)

logₐ x = ln x ÷ ln a

\log_{a} x = \dfrac{\ln x}{\ln a}

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <msub><mi>log</mi><mi>a</mi></msub>
    <mi>x</mi>
    <mo>=</mo>
    <mfrac>
      <mrow><mi>ln</mi><mo>&#x2061;</mo><mi>x</mi></mrow>
      <mrow><mi>ln</mi><mo>&#x2061;</mo><mi>a</mi></mrow>
    </mfrac>
  </mrow>
</math>

log_a x = (ln x)/(ln a)

Log[x]/Log[a]

y := ln(x)/ln(a);

y = log(x)/log(a);

log_a(x) = ln(x)/ln(a)

Finding the base (from the argument and the log value)

a = x^{1/y}

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <mi>a</mi>
    <mo>=</mo>
    <msup>
      <mi>x</mi>
      <mrow><mn>1</mn><mo>/</mo><mi>y</mi></mrow>
    </msup>
  </mrow>
</math>

a = x^(1/y)

x^(1/y)

a := x^(1/y);

a = x^(1/y);

a = x^(1/y)

Product rule (the log of a product is a sum)

logₐ(MN) = logₐ M + logₐ N

\log_{a} MN = \log_{a} M + \log_{a} N

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <msub><mi>log</mi><mi>a</mi></msub>
    <mrow><mi>M</mi><mi>N</mi></mrow>
    <mo>=</mo>
    <msub><mi>log</mi><mi>a</mi></msub>
    <mi>M</mi>
    <mo>+</mo>
    <msub><mi>log</mi><mi>a</mi></msub>
    <mi>N</mi>
  </mrow>
</math>

log_a (MN) = log_a M + log_a N

Log[a, M*n] == Log[a, M] + Log[a, n]  (* N (numerical evaluation) is a reserved word in Mathematica, so n is used instead *)

log[a](M*N) = log[a](M) + log[a](N);

log(M*N)/log(a) == log(M)/log(a) + log(N)/log(a)

log_a(MN) = log_a(M) + log_a(N)

Quotient rule (the log of a quotient is a difference)

logₐ(M ÷ N) = logₐ M − logₐ N

\log_{a} \dfrac{M}{N} = \log_{a} M - \log_{a} N

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <msub><mi>log</mi><mi>a</mi></msub>
    <mfrac><mi>M</mi><mi>N</mi></mfrac>
    <mo>=</mo>
    <msub><mi>log</mi><mi>a</mi></msub>
    <mi>M</mi>
    <mo>&#x2212;</mo>
    <msub><mi>log</mi><mi>a</mi></msub>
    <mi>N</mi>
  </mrow>
</math>

log_a (M/N) = log_a M - log_a N

Log[a, M/n] == Log[a, M] - Log[a, n]  (* N (numerical evaluation) is a reserved word in Mathematica, so n is used instead *)

log[a](M/N) = log[a](M) - log[a](N);

log(M/N)/log(a) == log(M)/log(a) - log(N)/log(a)

log_a(M/N) = log_a(M) - log_a(N)

Power rule (the exponent moves to the front)

logₐ(Mᵏ) = k logₐ M

\log_{a} M^{k} = k \log_{a} M

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <msub><mi>log</mi><mi>a</mi></msub>
    <msup><mi>M</mi><mi>k</mi></msup>
    <mo>=</mo>
    <mi>k</mi>
    <msub><mi>log</mi><mi>a</mi></msub>
    <mi>M</mi>
  </mrow>
</math>

log_a (M^k) = k log_a M

Log[a, M^k] == k*Log[a, M]

log[a](M^k) = k*log[a](M);

log(M^k)/log(a) == k*log(M)/log(a)

log_a(M^k) = k log_a(M)

How to have ChatGPT do the calculation

You are a calculation assistant for logarithms. Do the following calculations by actually running Python code, and base your answer only on the numbers from the execution result (do not answer by mental math or guessing).

Find each of the following:
1. The log of 100 with base 10 (log10(100))
2. The natural log of 7 (ln 7)
3. The argument when the base is 2 and the log value is 10 (2 to the 10th power)
4. The number whose 4th power is 81 (the base when the argument is 81 and the log value is 4)

Show the formulas you used and the numbers from the execution result.

How to Use

1

Enter your numbers

Type the numbers you want to calculate with into the input fields
2

Calculate

Press the "Calculate" button
3

Check the result

The result appears on the spot. The same page also explains the idea behind the calculation and the formula