One Rep Max Calculator
Your one rep max (1RM) is the heaviest weight you can lift once with good form. Testing it directly is tiring and risky, so lifters estimate it from a lighter set. Enter the weight and the reps you managed.
Type a number and the answer appears straight away.
Estimated one rep max215.8 lbEpley formula
- Brzycki formula
- 208.1 lb
- Average of the two
- 212 lb
Estimates only. Do not test a true one rep max without a spotter or safety bars.
| % of max | Weight (lb) | Typical reps |
|---|---|---|
| 100% | 215.8 | 1 |
| 95% | 205 | 2 |
| 90% | 194.3 | 3 |
| 85% | 183.5 | 5 |
| 80% | 172.7 | 8 |
| 75% | 161.9 | 10 |
| 70% | 151.1 | 13 |
| 65% | 140.3 | 16 |
| 60% | 129.5 | 20 |
The math behind it: One Rep Max
Epley: 1RM = weight x (1 + reps / 30); Brzycki: 1RM = weight x 36 / (37 - reps)
The calculator shows the Epley estimate first and the Brzycki estimate beside it. Lifting 185 lb for 5 reps gives 215.8 lb by Epley and 208.1 lb by Brzycki. Both formulas are most accurate for sets of 10 reps or fewer.
Common questions
How do I calculate my one rep max?
Multiply the weight by 1 plus the number of reps divided by 30. For 185 lb lifted 5 times: 185 x (1 + 5 / 30) = 215.8 lb. This is the Epley formula.
How accurate is a one rep max calculator?
Usually within about 5% for sets of 2 to 10 reps. Accuracy falls with higher reps, and it varies between lifts and lifters, so treat the number as an estimate.
What percentage of my one rep max should I train with?
It depends on the goal. Strength work is typically 85% or more for 1 to 5 reps, muscle building is 65% to 85% for 6 to 12 reps, and endurance work is below 65% for 15 reps or more.
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