One rep max calculator
Enter the weight and reps from a recent set to estimate your one rep max (1RM) without testing a maximal lift.
| % of 1RM | Weight | About this many reps |
|---|---|---|
| 100% | 116.5 kg | 1 |
| 95% | 111 kg | 2 |
| 90% | 105 kg | 3 |
| 85% | 99 kg | 5 |
| 80% | 93.5 kg | 8 |
| 75% | 87.5 kg | 10 |
| 70% | 81.5 kg | 13 |
| 65% | 76 kg | 16 |
| 60% | 70 kg | 20 |
| 55% | 64 kg | 25 |
| 50% | 58.5 kg | 30 |
How the 1RM calculator works
A one rep max is the heaviest weight you can lift once with good form. Lifting a lighter weight for several reps lets you estimate it. This calculator uses the same formulas as the 1RM Calculator app:
- Epley: 1RM = weight × (1 + reps ÷ 30)
- Brzycki: 1RM = weight × 36 ÷ (37 − reps)
- Lombardi: 1RM = weight × reps^0.10
Example: 100 kg for 5 reps gives an Epley estimate of 116.5 kg. A single rep is taken as your 1RM as it is.
The chart below the result turns your 1RM into training weights. The rep counts next to each percentage come from the Epley formula in reverse, so they are a guide, not a rule.
Questions
Which 1RM formula is most accurate?
They agree closely between 2 and 10 reps. Epley tends to give slightly higher estimates at higher reps and Brzycki slightly lower ones. Use the same formula each time so your estimates are comparable.
How many reps should I use?
Sets of 2 to 10 reps give the most reliable estimates. Above about 10 reps, endurance matters more and every formula gets less accurate.
Is it safe to test a true one rep max?
Estimating from a submaximal set is safer and less tiring than a true max attempt. If you do test a max, use a spotter or safety bars.
See your strength rank
The 1RM Calculator app compares your lifts with bodyweight-based strength standards and saves your lift history.