Enter the weight you lifted (kg) and how many reps in a row you did with it. Your 1RM (the most you can lift for one rep) is estimated with three formulas, with a table by reps, a %1RM lookup table and a graph.
Enter the weight in kg and the reps as a whole number from 1 to 10. A weight you can lift for no more than 3 to 10 reps gives a more accurate estimate. The results come from rules of thumb and do not guarantee what you can actually lift.
Result and graph
Enter the weight you lifted and the number of reps on the left and press "Calculate". The result and a graph will appear here.
Table of Contents
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What you can do on this page
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What is this calculation used for?
-
How to Use
-
Formulas and graphs
-
Symbols and terms
-
Good to know before you start
-
How to calculate it in Excel
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How to calculate it in Google Sheets
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How to calculate it in Python
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How to write it in LaTeX and other math languages (copy and paste)
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How to have ChatGPT do the calculation
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DataChef Features
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Related Features
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NumberChef Calculators List
What you can do on this page
- From a set such as "I lifted this weight for so many reps in a row" on the bench press or squat, estimate the most you could lift for a single rep (your 1RM)
- Enter the weight (lb) and the reps (1 to 10) to see the estimated 1RM from three formulas at once: Epley (standard), Brzycki and Lombardi
- From your estimated 1RM, a table shows the weight for each number of reps, and a lookup table shows the weight and reps for each %1RM (percentage of your 1RM). You can use them directly to plan your training weights
- A graph of weight against reps shows your set and your estimated 1RM at a glance
- A plain-language explanation of the formulas and copy-and-paste formulas for Excel, Google Sheets and Python are all on this page
The estimated 1RM comes from statistical rules of thumb and is only a guide. What you can actually lift depends on the exercise, your experience and how you feel that day. When you attempt a heavy weight, always use a spotter and put correct form first. If you are new to lifting, it is safer not to test your true one-rep max and to use the formulas for an estimate instead.
What is this calculation used for?
Choosing training weights to fit your goal (using %1RM)
In strength training, the basic idea is to plan your workouts as "so many reps at such a percentage of your 1RM", depending on your goal. Common guidelines from the National Strength and Conditioning Association (NSCA) are 85% of 1RM or more for 6 reps or fewer to build strength, 67–85% for 6 to 12 reps to build muscle size, and 67% or less for 12 reps or more for muscular endurance.
Once you can estimate your 1RM, each %1RM becomes an actual weight. For example, if 225 lb for 5 reps gives an estimated 1RM of 262.5 lb, 75% of that for muscle size is about 197 lb. It goes straight into setting the weight for today's workout.
Estimating your max without a risky all-out attempt
To measure a true 1RM, you have to attempt your limit, and a very heavy attempt comes with the risk of failing under the bar and heavy stress on your joints and tendons. With the formulas, you can get an estimate of your 1RM from an everyday set such as "225 lb × 5", without going to your limit.
Especially for newer lifters, the usual advice is to avoid testing a true 1RM before your form is solid. The formulas are widely used as a safe alternative.
Planning attempts in powerlifting and other strength sports
In powerlifting and weightlifting, your result is the heaviest single lift you make at a meet. You cannot go to your limit at every training session, so lifters calculate an estimated 1RM from their training sets of "weight × reps", follow how it changes, and use it to plan the weights they will attempt at the meet. In most powerlifting meets, attempts are declared in kilograms, so switching "Units" to Metric can help.
If a team uses the same formula as a common measure, it is also easier to compare progress between lifters of different sizes and in different lifts.
Setting a safe load in rehab and exercise for older adults
In rehabilitation and exercise programs for older adults, the load for strength training is sometimes set as a percentage of 1RM. Having someone with limited strength lift a maximum weight is dangerous, so estimating the 1RM from how many reps they can do with a light weight is considered the better approach.
In this way, the formulas are a tool not only for athletes but also for people who want to exercise with safety first. Rehab and exercise for people with health conditions should always be done under the guidance of a doctor, physical therapist or other professional.
Formulas and graphs
Epley formula (the standard on this page)
Graph
Standard notation
(the usual math form)
\(M\)
\(=\)
\(W\)
\(\times\)
\((\)
\(1\)
\(+\)
\(r\)
\(\div\)
\(30\)
\()\)
In words
(symbols replaced with words)
⑤
\(M\): estimated 1RM (lb)
\(=\)
④
\(W\): weight lifted (lb)
\(\times\)
\((\)
③
constant \(1\)
\(+\)
①
\(r\): reps
\(\div\)
②
constant \(30\)
\()\)
The formula in words
①
Take the
\(r\): reps
②
divide by the
constant \(30\)
③
add the
constant \(1\)
④
multiply the result by the
\(W\): weight lifted (lb)
⑤
and you get the
\(M\): estimated 1RM (lb)
Quick example
For someone who can bench press 100 lb for 5 reps in a row, the 1RM by the Epley formula is
estimated 1RM (lb)
\(=\)
weight lifted (100 lb)
\(\times\)
\((\)
constant 1
\(+\)
reps (5)
\(\div\)
constant 30
\()\)
\(100 \times \left(1 + \dfrac{5}{30}\right) = 100 \times \dfrac{35}{30} \approx 116.7\ \mathrm{lb}\)
Key idea
The Epley formula is the most widely used formula for estimating a 1RM, and it is the standard (default) in this calculator. It is a simple linear formula in the number of reps, built on the idea that the weight you can lift 30 times is exactly half your 1RM. Each extra rep raises the estimated 1RM by 1/30 (about 3.3%) of the weight lifted.
When the reps are 1, the weight itself is what you actually lifted once, your measured 1RM. So in this calculator, no formula is used and estimated 1RM = weight lifted.
The formula works the same in any unit: enter pounds and you get pounds, enter kg and you get kg.
Brzycki formula
Graph
Standard notation
(the usual math form)
\(M\)
\(=\)
\(W\)
\(\times\)
\(36\)
\(\div\)
\((\)
\(37\)
\(-\)
\(r\)
\()\)
In words
(symbols replaced with words)
⑤
\(M\): estimated 1RM (lb)
\(=\)
④
\(W\): weight lifted (lb)
\(\times\)
③
constant \(36\)
\(\div\)
\((\)
①
constant \(37\)
\(-\)
②
\(r\): reps
\()\)
The formula in words
①
From the
constant \(37\)
②
subtract the
\(r\): reps
③
divide the
constant \(36\)
by that result
④
multiply by the
\(W\): weight lifted (lb)
⑤
and you get the
\(M\): estimated 1RM (lb)
Quick example
For someone who can squat 80 lb for 10 reps in a row, the 1RM by the Brzycki formula is
estimated 1RM (lb)
\(=\)
weight lifted (80 lb)
\(\times\)
constant 36
\(\div\)
\((\)
constant 37
\(-\)
reps (10)
\()\)
\(80 \times \dfrac{36}{37 - 10} = 80 \times \dfrac{36}{27} \approx 106.7\ \mathrm{lb}\)
Key idea
The difference from the Epley formula is that the reps are in the denominator (the number you divide by). With few reps it gives a more cautious estimate than Epley, and at exactly 10 reps it gives the same value as Epley (\(\dfrac{4}{3}\) times the weight lifted).
Because the denominator is "37 − reps", the more reps, the smaller the denominator, and the estimated 1RM grows quickly. Used with high-rep sets, it tends to overestimate, so this calculator allows at most 10 reps. With 1 rep, \(36 \div (37-1) = 1\), so the formula itself also gives estimated 1RM = weight lifted.
Lombardi formula
Graph
Standard notation
(the usual math form)
\(M\)
\(=\)
\(W\)
\(\times\)
\(r\)
\(0.1\)
In words
(symbols replaced with words)
④
\(M\): estimated 1RM (lb)
\(=\)
③
\(W\): weight lifted (lb)
\(\times\)
①
\(r\): reps
②
to the power \(0.1\)
The formula in words
①
Take the
\(r\): reps
②
raise it
to the power \(0.1\)
③
multiply by the
\(W\): weight lifted (lb)
④
and you get the
\(M\): estimated 1RM (lb)
Quick example
For someone who can deadlift 100 lb for 8 reps in a row, the 1RM by the Lombardi formula is
estimated 1RM (lb)
\(=\)
weight lifted (100 lb)
\(\times\)
reps (8)
to the power 0.1
\(100 \times 8^{0.1} \approx 100 \times 1.231 \approx 123.1\ \mathrm{lb}\)
Key idea
The Lombardi formula multiplies by the reps raised to the power 0.1 (the number that gives back the reps when raised to the 10th power). A decimal power such as \(0.1\) is not practical by hand, so use this calculator, Excel or the power key on a calculator.
With few reps it gives values close to Epley, but as the reps go up, its estimate grows the most slowly of the three, and at 8 reps or more it gives the most cautious estimate. That is why it rarely gives extreme values for high-rep sets. With 1 rep, \(1^{0.1} = 1\), so the formula itself also gives estimated 1RM = weight lifted.
Working back to the weight for a number of reps and its %1RM (Epley formula)
Graph
Standard notation
(the usual math form)
\(w\)
\(=\)
\(M\)
\(\div\)
\((\)
\(1\)
\(+\)
\(r\)
\(\div\)
\(30\)
\()\)
\(R\)
\(=\)
\(w\)
\(\div\)
\(M\)
\(\times\)
\(100\)
In words
(symbols replaced with words)
⑤
\(w\): weight you can lift for that many reps (lb)
\(=\)
①
\(M\): estimated 1RM (lb)
\(\div\)
\((\)
④
constant \(1\)
\(+\)
②
\(r\): reps
\(\div\)
③
constant \(30\)
\()\)
⑨
\(R\): %1RM (%)
\(=\)
⑥
\(w\): weight you can lift for that many reps (lb)
\(\div\)
⑦
\(M\): estimated 1RM (lb)
\(\times\)
⑧
\(100\) to make a percentage
The formula in words
①
Take the
\(M\): estimated 1RM (lb)
②
divide the
\(r\): reps
③
by the
constant \(30\)
④
add the
constant \(1\)
and divide the 1RM by this sum
⑤
This gives the
\(w\): weight you can lift for that many reps (lb)
⑥
Then divide the
\(w\): weight you can lift for that many reps (lb)
⑦
by the
\(M\): estimated 1RM (lb)
⑧
multiply by
\(100\) to make a percentage
⑨
and you get the
\(R\): %1RM (%)
Quick example
For someone with an estimated 1RM of 116.7 lb, the weight they can lift for 10 reps and its %1RM are
weight for 10 reps (lb)
\(=\)
estimated 1RM (116.7 lb)
\(\div\)
\((\)
constant 1
\(+\)
reps (10)
\(\div\)
constant 30
\()\)
%1RM (%)
\(=\)
weight for 10 reps (87.5 lb)
\(\div\)
estimated 1RM (116.7 lb)
\(\times\)
100 to make a percentage
\(116.7 \div \left(1 + \dfrac{10}{30}\right) = 116.7 \div \dfrac{4}{3} \approx 87.5\ \mathrm{lb}\)
\(87.5 \div 116.7 \times 100 \approx 75\ (\%)\)
Key idea
Using a 1RM formula backward tells you "with this estimated 1RM, how much can I lift for this many reps?" The table by reps and the %1RM lookup table in this calculator are built by working the chosen formula backward like this (for Brzycki, \(w = M \times (37 - r) \div 36\); for Lombardi, \(w = M \div r^{0.1}\)).
%1RM (a percentage of your 1RM) is used as a common measure of training intensity. The "Reps you can do (guide)" in the %1RM lookup table is the result of working the formula backward, with the decimal part dropped.
Your 1RM (one-rep max) can be estimated from a set of "weight × reps" with rules-of-thumb formulas. The standard is the Epley formula, which adds 1/30 of the weight lifted for each extra rep. Worked backward, the same formulas give the weight for any number of reps and its %1RM, a useful measure for setting training weights.
Symbols and terms
Symbols
| \(M\) | em | The estimated 1RM you want to find (lb or kg). M stands for "maximum". |
| \(W\) | double-u | The weight lifted (lb or kg), the weight you actually lifted for several reps in a row. W stands for "weight". |
| \(r\) | ar | The reps, how many times in a row you lifted that weight. r stands for "repetitions". |
| \(r^{0.1}\) | r to the power 0.1 | The reps raised to the power 0.1. The exponent (the small number at the upper right) is a decimal, which is not practical by hand, so use the power key on a calculator or "^" in Excel. It is used in the Lombardi formula. |
| \(w\) | lowercase double-u | The estimated weight you can lift for a given number of reps, worked back from the estimated 1RM (lb or kg). It is lowercase to tell it apart from capital \(W\) (the weight you entered). |
| \(R\) | capital ar | %1RM (a percentage of your 1RM). It shows what percentage of your estimated 1RM a weight is. |
Terms
| 1RM | The most weight you can lift for a single rep with correct form. It is short for one-repetition maximum, often called your one-rep max or simply your max. It is a standard measure of strength and the basis for setting training weights. |
| RM | Short for repetition maximum, used almost like a unit for "the weight at which that many reps is exactly your limit". For example, your 5RM is the weight you can lift for 5 reps in a row and no more. 1RM is the one-rep version. |
| rep | Short for repetition, one complete movement of an exercise. In training, the number of times you repeat the movement in a row is counted in reps, as in "3 sets of 10 reps". It is the same as \(r\) on this page. |
| %1RM | A measure of training intensity that shows what percentage of your 1RM a weight is. For example, 200 lb for someone with a 1RM of 250 lb is 80% of 1RM. Choosing the %1RM and reps to match your goal (strength, muscle size or muscular endurance) is the basic way to plan strength training. |
| Epley formula | The most widely used formula for estimating a 1RM, and the standard in this calculator. It is a linear formula in which each extra rep raises the estimated 1RM by 1/30 of the weight lifted. |
| Brzycki formula | A 1RM formula with the reps in the denominator. With few reps it gives a more cautious estimate than Epley, and at exactly 10 reps it gives the same value as Epley. |
| Lombardi formula | A 1RM formula that multiplies by the reps raised to the power 0.1. Its estimate grows slowly as the reps go up, so it rarely gives extreme values. |
| spotter | A helper who supports the bar if you cannot finish a rep. When you attempt a heavy weight in an exercise where the weight could fall on you, such as the bench press, using a spotter is a basic safety rule. |
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.
| Percentages (Grade 6) |
|
| Fractions and division (Grades 5–6) |
|
| Substituting into expressions (Grades 6–7) |
|
| Powers and exponents (Grade 6 and up) |
|
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 estimated 1RM (Epley formula)
| Weight lifted W (lb) | 225 |
| Reps r | 5 |
| Estimated 1RM (lb) | =IF(B2=1,B1,B1*(1+B2/30)) |
Table to find the estimated 1RM (Brzycki formula)
| Weight lifted W (lb) | 225 |
| Reps r | 5 |
| Estimated 1RM (lb) | =B1*36/(37-B2) |
Table to find the estimated 1RM (Lombardi formula)
| Weight lifted W (lb) | 225 |
| Reps r | 5 |
| Estimated 1RM (lb) | =B1*B2^0.1 |
Table to work back to the weight for a number of reps and its %1RM (Epley formula)
| Estimated 1RM M (lb) | 262.5 |
| Reps you want r | 10 |
| Weight you can lift for those reps (lb) | =IF(B2=1,B1,B1/(1+B2/30)) |
| %1RM (%) | =ROUND(B3/B1*100,0) |
After pasting, the upper rows are your inputs and the formula rows are calculated automatically.
"^" is the power sign (how many times a number is multiplied by itself), and "ROUND(value,0)" rounds to a whole number. The "IF(B2=1,B1,…)" in the first and fourth tables gives back the weight you entered (your measured 1RM) without using the formula when the reps are 1, the same rule as this calculator.
For 225 lb × 5 reps, the first table shows 262.5, the second 253.125 and the third about 264.3. The fourth table gives a weight of about 196.9 lb and a %1RM of 75. Just replace the weight and reps with your own set. It works the same in kg.
"^" is the power sign (how many times a number is multiplied by itself), and "ROUND(value,0)" rounds to a whole number. The "IF(B2=1,B1,…)" in the first and fourth tables gives back the weight you entered (your measured 1RM) without using the formula when the reps are 1, the same rule as this calculator.
For 225 lb × 5 reps, the first table shows 262.5, the second 253.125 and the third about 264.3. The fourth table gives a weight of about 196.9 lb and a %1RM of 75. Just replace the weight and reps with your own set. It works the same in kg.
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 estimated 1RM (Epley formula)
| Weight lifted W (lb) | 225 |
| Reps r | 5 |
| Estimated 1RM (lb) | =IF(B2=1,B1,B1*(1+B2/30)) |
Table to find the estimated 1RM (Brzycki formula)
| Weight lifted W (lb) | 225 |
| Reps r | 5 |
| Estimated 1RM (lb) | =B1*36/(37-B2) |
Table to find the estimated 1RM (Lombardi formula)
| Weight lifted W (lb) | 225 |
| Reps r | 5 |
| Estimated 1RM (lb) | =B1*B2^0.1 |
Table to work back to the weight for a number of reps and its %1RM (Epley formula)
| Estimated 1RM M (lb) | 262.5 |
| Reps you want r | 10 |
| Weight you can lift for those reps (lb) | =IF(B2=1,B1,B1/(1+B2/30)) |
| %1RM (%) | =ROUND(B3/B1*100,0) |
The same formulas as in Excel work as is. Copy the whole table, paste it into cell A1, and replace the weight and reps with your own set.
How to calculate it in Python
weight_lb = 225 # weight lifted (lb)
reps = 5 # reps (1 to 10)
if reps == 1:
# A weight lifted once is itself your measured 1RM (the weight entered, whatever the formula)
epley = brzycki = lombardi = weight_lb
else:
epley = weight_lb * (1 + reps / 30) # Epley formula (standard)
brzycki = weight_lb * 36 / (37 - reps) # Brzycki formula
lombardi = weight_lb * reps ** 0.1 # Lombardi formula
print(f"Epley formula: {epley:.1f} lb")
print(f"Brzycki formula: {brzycki:.1f} lb")
print(f"Lombardi formula: {lombardi:.1f} lb")
# Weight for each %1RM (using the Epley estimated 1RM)
for pct in range(100, 45, -5):
print(f"{pct}% of 1RM: {epley * pct / 100:.1f} lb")
Runs with the standard library only. "**" is the power sign. Change the weight and reps at the top to your own set and run it. When the reps are 1, it follows the same rule as this calculator (estimated 1RM = the weight entered).
How to write it in LaTeX and other math languages (copy and paste)
Epley formula (the standard on this page)
M = W × (1 + r ÷ 30)
M = W \left(1 + \dfrac{r}{30}\right)
<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
<mrow>
<mi>M</mi>
<mo>=</mo>
<mi>W</mi>
<mrow>
<mo>(</mo>
<mn>1</mn>
<mo>+</mo>
<mfrac><mi>r</mi><mn>30</mn></mfrac>
<mo>)</mo>
</mrow>
</mrow>
</math>
M = W(1 + r/30)
W*(1 + r/30)
M := W*(1 + r/30);
M = W*(1 + r/30);
M = W(1 + r/30)
Brzycki formula
M = W × 36 ÷ (37 − r)
M = W \times \dfrac{36}{37 - r}
<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
<mrow>
<mi>M</mi>
<mo>=</mo>
<mi>W</mi>
<mo>×</mo>
<mfrac>
<mn>36</mn>
<mrow><mn>37</mn><mo>−</mo><mi>r</mi></mrow>
</mfrac>
</mrow>
</math>
M = W xx 36/(37 - r)
36*W/(37 - r)
M := 36*W/(37 - r);
M = 36*W/(37 - r);
M = 36W/(37 − r)
Lombardi formula
M = W \times r^{0.1}
<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
<mrow>
<mi>M</mi>
<mo>=</mo>
<mi>W</mi>
<mo>×</mo>
<msup><mi>r</mi><mn>0.1</mn></msup>
</mrow>
</math>
M = W xx r^(0.1)
W*r^0.1
M := W*r^0.1;
M = W*r^0.1;
M = W r^0.1
Working back to the weight for a number of reps and its %1RM (Epley formula)
w = M ÷ (1 + r ÷ 30), R = w ÷ M × 100
w = \dfrac{M}{1 + \dfrac{r}{30}}, \quad R = \dfrac{w}{M} \times 100
<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
<mrow>
<mi>w</mi>
<mo>=</mo>
<mfrac>
<mi>M</mi>
<mrow><mn>1</mn><mo>+</mo><mfrac><mi>r</mi><mn>30</mn></mfrac></mrow>
</mfrac>
<mo>,</mo>
<mi>R</mi>
<mo>=</mo>
<mfrac><mi>w</mi><mi>M</mi></mfrac>
<mo>×</mo>
<mn>100</mn>
</mrow>
</math>
w = M/(1 + r/30), R = w/M xx 100
{M/(1 + r/30), 100*w/M}
w := M/(1 + r/30); R := 100*w/M;
w = M/(1 + r/30); R = 100*w/M;
w = M/(1 + r/30), R = w/M × 100
How to have ChatGPT do the calculation
You are a strength training calculation assistant. Do the following calculation 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). I bench pressed 225 lb for 5 reps in a row. Estimate my 1RM (the most I can lift for one rep) with each of these three formulas (keep the weight in pounds). 1. Epley formula: weight lifted × (1 + reps ÷ 30) 2. Brzycki formula: weight lifted × 36 ÷ (37 − reps) 3. Lombardi formula: weight lifted × reps to the power 0.1 If the reps are 1, do not use a formula; the 1RM is the weight lifted itself. Then, using the Epley estimate, list the weight for each %1RM from 100% down to 50% in steps of 5% (in lb, to one decimal place). Show the formulas you used and the numbers from the execution result. Also note that these are estimates from rules of thumb and do not guarantee what I can actually lift.
How to Use
-
1Enter your numbersType the numbers you want to calculate with into the input fields
-
2CalculatePress the "Calculate" button
-
3Check the resultThe result appears on the spot. The same page also explains the idea behind the calculation and the formula
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