One-Rep Max Calculator

Estimate one-rep max from the weight lifted and repetitions completed.

How to use One-Rep Max Calculator

1. Enter Weight Lifted, Repetitions, Formula, Weight Unit. 2. These are declared model estimates, not measured maxima or safe-load instructions. One repetition returns the entered weight. Repetitions are positive whole counts; Brzycki/Lander reject non-positive denominators. Exercise, effort, fatigue and higher repetition counts affect how an estimate should be interpreted. 3. Select Calculate or press Enter. 4. Select Copy result to copy the answer, or Reset to clear the form and result.

Why use this tool?

These are declared model estimates, not measured maxima or safe-load instructions. One repetition returns the entered weight. Repetitions are positive whole counts; Brzycki/Lander reject non-positive denominators. Exercise, effort, fatigue and higher repetition counts affect how an estimate should be interpreted.

How the calculation works

Epley: weight × (1 + reps/30). Brzycki: weight × 36/(37 − reps). Lander: 100 × weight/(101.3 − 2.67123 × reps). Lombardi: weight × reps^0.1. These are declared model estimates, not measured maxima or safe-load instructions. One repetition returns the entered weight. Repetitions are positive whole counts; Brzycki/Lander reject non-positive denominators. Exercise, effort, fatigue and higher repetition counts affect how an estimate should be interpreted. This quantity displays up to two decimal places where applicable. Durations round to the nearest second; nonzero subsecond durations are labelled. Changing unit labels does not convert entered quantities.

Example

Worked example: Weight Lifted = 100; Repetitions = 6; Formula = "Epley"; Weight Unit = "kg". Result: 120 kg (estimated Epley 1RM).

Practical tip

Treat the displayed model value as an estimate, with the exercise and repetition/effort basis kept alongside it.