One rep max calculator.
Your estimated max, from one set.
Kilograms only. Enter the weight lifted and the reps performed with it.
Estimated one rep max kg
Enter the weight and the reps.
By model
- Brzycki —
- O'Conner —
- Epley —
- Lombardi —
- Mayhew —
Warm-up ladder
Four sets to the estimated max, each rounded to 2.5 kg.
- 40% × 8 —
- 60% × 5 —
- 75% × 3 —
- 90% × 1 —
- Estimated max —
Five published estimates.
Each model is implemented exactly as its author published it, and the headline figure is their average. w is the weight lifted, r the reps performed.
Brzycki
w × 36 ÷ (37 − r). Matt Brzycki (1993), “Strength testing — predicting a one-rep max from reps-to-fatigue”, Journal of Physical Education, Recreation & Dance 64(1). Usually printed as w ÷ (1.0278 − 0.0278r), which is the same equation with its fractions truncated; the exact form is used here.
O'Conner
w × (1 + 0.025r). Bob O'Conner, Jerry Simmons and J. Patrick O'Shea (1989), Weight Training Today.
Epley
w × (1 + r ÷ 30). Boyd Epley (1985), Poundage Chart, Boyd Epley Workout, University of Nebraska.
Lombardi
w × r0.10. V. Patteson Lombardi (1989), Beginning Weight Training.
Mayhew
100w ÷ (52.2 + 41.9e−0.055r). Jerry Mayhew and colleagues (1992), Journal of Applied Sport Science Research 6(4).
The warm-up ladder
Four sets at 40, 60, 75 and 90 per cent of the estimated max, reps tapering from eight to one, each weight rounded to the nearest 2.5 kg — the smallest step a barbell loads with a 1.25 kg plate on each side. Each bar is that set's share of the max, drawn to scale. The percentages prime the movement without spending the max; the scheme is the conventional attempt-day taper.
These are estimates from reps to fatigue, not measurements: the only true test of a one rep max is lifting it. They hold best at ten reps or fewer, which is why the reps field stops at fifteen.
Every result is calculated locally. Nothing is stored and nothing is sent anywhere.
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