One-Rep Max Calculator

Both the Epley and Brzycki formulas are shown. Above about 10 reps the two diverge, so a set of 5–8 gives the most reliable estimate.

Your numbers

Weight lifted (kg)Reps

1RM

101.3kg

Result

99.3kg

Formula

1RM = Weight lifted (kg) × (1 + Reps ÷ 30) (Epley)

This is an estimate — attempt a true 1RM only with a spotter and a full warm-up.

What to enter

Input	Default	Accepted range
Weight lifted (kg)The weight you actually lifted.	80	1 ~ 500
RepsHow many times you lifted it.	8	1 ~ 20

Step by step

Formula1RM = Weight lifted (kg) × (1 + Reps ÷ 30) (Epley)

With the default numbers1RM = 80 × (1 + 8 ÷ 30) (Epley)

Answer1RM = 101.3 kg

Quick reference table

Results when only Weight lifted (kg) changes and everything else stays put.

Weight lifted (kg)	1RM (kg)	Result (kg)
40	50.7	49.7
60	76	74.5
80	101.3	99.3
120	152	149
160	202.7	198.6

What each result means

Result	At default values
1RM (kg)The most you could lift exactly once — an estimate.	101.3
Result (kg)What the formula gives back — the answer this page is for.	99.3

Common mistakes

This is an estimate — attempt a true 1RM only with a spotter and a full warm-up.

Glossary

Weight lifted (kg): The weight you actually lifted.
Reps: How many times you lifted it.
1RM: The most you could lift exactly once — an estimate.
Result: What the formula gives back — the answer this page is for.

Frequently asked questions

QHow is One-Rep Max Calculator calculated?

1RM = Weight lifted (kg) × (1 + Reps ÷ 30) (Epley) — Both the Epley and Brzycki formulas are shown. Above about 10 reps the two diverge, so a set of 5–8 gives the most reliable estimate.

QCan you walk through an example?

With Weight lifted (kg) 80, Reps 8, the answer is 1RM 101.3kg.

QWhat do I need to enter?

Enter Weight lifted (kg), Reps. The result recalculates as you type, and an empty box counts as zero.

QHow much does the answer move if I change a number?

Changing only Weight lifted (kg) moves the answer to Weight lifted (kg) 40 → 1RM (kg) 50.7 and Weight lifted (kg) 160 → 1RM (kg) 202.7. The table below lays out five steps.

QHow are the numbers rounded?

Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.

QAnything to watch out for?

This is an estimate — attempt a true 1RM only with a spotter and a full warm-up.

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These calculators help you understand health figures; they do not replace diagnosis or prescription. See a clinician if you have symptoms.