One-Rep Max Calculator
Estimate the most you could lift once, from a set you have actually done. Two published formulas are shown rather than one, because they disagree, and the gap between them is a fair picture of how much of an estimate this is.
Estimate your one-rep max
Frequently Asked Questions
The heaviest weight you could lift once with good form. It is used to set training loads as a percentage of that maximum.
Because the two standard formulas disagree, and the spread is honest. Epley (1985) uses weight × (1 + reps/30); Brzycki (1993) uses weight × 36 / (37 − reps). At five reps they are within a couple of percent; at twelve they are not.
Fewer is better. These formulas were fitted to sets of around two to ten, and beyond that they drift, which is why this one flags an estimate taken from more than ten.
That is a training decision rather than an arithmetic one, and it carries real injury risk without coaching and a spotter. The estimate exists so that most people never need to.