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
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
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
Q. How 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.
Q. Can you walk through an example?
With Weight lifted (kg) 80, Reps 8, the answer is 1RM 101.3kg.
Q. What do I need to enter?
Enter Weight lifted (kg), Reps. The result recalculates as you type, and an empty box counts as zero.
Q. How 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.
Q. How 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.
Q. Anything 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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