Estimate your one-rep max (1RM) from a weight and rep count you can currently lift, using the Epley and Brzycki formulas, plus common training percentages of your max.
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Since maxing out on every lift isn't practical or safe for most training, one-rep max (1RM) is commonly estimated from a lighter set taken close to failure. This calculator uses two widely cited formulas: Epley, 1RM = Weight × (1 + Reps ÷ 30), and Brzycki, 1RM = Weight × (36 ÷ (37 − Reps)). The two formulas tend to agree closely at low rep counts and diverge somewhat at higher reps, which is why both are shown alongside their average.
Many strength programs prescribe working sets as a percentage of your 1RM (for example, '5 sets of 5 at 80% of max'). This calculator shows your estimated max at several common training percentages, so you can quickly translate a percentage-based program into actual weight on the bar.
It's a reasonably close estimate for most people when based on a set of 10 reps or fewer taken close to failure, but individual factors like muscle fiber type and training experience mean actual 1RM can differ from the estimate by a meaningful margin.
Epley and Brzycki were derived from different data sets and use different mathematical relationships between reps and percentage of max, so they naturally diverge somewhat, especially at higher rep counts. Neither is universally 'more correct', which is why this calculator shows both.
That's a personal training decision best made with appropriate experience, warm-up and, ideally, a spotter. Many lifters find estimated 1RM from submaximal sets is perfectly sufficient for programming purposes without needing to test a true max.
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