One-rep max calculator
Estimate your one-repetition maximum from a set with six published formulas.
A clear answer. Here’s how.
Estimates the heaviest single repetition from a hard set using six published formulas: Epley w(1 + r/30), Brzycki 36w/(37 − r), Lombardi w·r^0.10, Mayhew 100w/(52.2 + 41.9e^(−0.055r)), O’Conner w(1 + 0.025r) and Wathan 100w/(48.8 + 53.8e^(−0.075r)). The mean smooths their differences, and training loads are percentages of it. Valid for 1–12 repetitions taken close to failure; one repetition returns the weight itself.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Weight lifted
- 100
- Repetitions completed
- 5
- Weight unit
- Kilograms
Example result
- Epley estimate
- 116.7
- Brzycki estimate
- 112.5
- Lombardi estimate
- 117.5
- Mayhew estimate
- 119
- O’Conner estimate
- 112.5
- Wathan estimate
- 116.6
- Mean of the six formulas
- 115.8
- 90% of estimated max
- 104.2
- 80% of estimated max
- 92.6
- 70% of estimated max
- 81.1
- 60% of estimated max
- 69.5
Each formula predicts the heaviest single repetition from a set to near-failure. They agree best for 2–10 repetitions; one repetition returns the weight lifted. Estimates are not a safe-load guarantee: warm up, use a spotter and test heavy lifts carefully.