1RM Calculator
Estimate your one-rep max from any set without testing it, compare the five classic formulas and get your training loads by percentage.
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A strength coach programs your loads, your progression and your technique around these numbers. See the strength training and strength and conditioning coaches.
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Example
A set of 5 reps at 225 lb gives an estimated 1RM of about 262 lb (Epley 262, Brzycki 253, Wathan 258). 80 % of that is 210 lb.
Method and formula
Epley: w × (1 + reps/30). Brzycki: w × 36 / (37 − reps). Lombardi: w × reps^0.10. O'Conner: w × (1 + 0.025 × reps). Wathan: 100 × w / (48.8 + 53.8 × e^(−0.075 × reps)).
The headline number averages Epley, Brzycki and Wathan, the three that agree best in the 2 to 10 rep range. The percentage table uses standard rep-to-percent charts.
Limits
- Accuracy is best for sets of 2 to 6 reps close to failure; above 10 reps formulas diverge by 5 to 10 %.
- Exercise matters: deadlift and squat estimates run higher than bench for the same reps.
FAQ
Which 1RM formula is most accurate?
Epley and Brzycki are the most used and nearly identical up to 10 reps. Wathan tracks well at higher reps. We average the three.
Should I test my real max?
Only if you are experienced and warmed up properly. For programming, an estimate from a 3 to 5 rep set is safer and accurate enough.
Free educational tool. Results are estimates from published formulas.