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One Rep Max (1RM) Calculator

Enter the weight and reps of a hard set to estimate your one-rep max and your training loads at every percentage.

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Estimated values

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What is it?

Your one-rep max (1RM) is the most weight you can lift once with good technique. It's used to plan training intensities without having to test a true max.

How it's calculated

We average three validated formulas: Epley, Brzycki and Lombardi.

Estimates are most accurate between 2 and 10 repetitions.

Epley: 1RM = w × (1 + reps/30)
Brzycki: 1RM = w × 36 / (37 − reps)
Lombardi: 1RM = w × reps^0.10

How we calculate · Last reviewed: September 1, 2026

How to interpret your result

Use the percentage table to choose working weights, e.g. ~75–80% for sets of 8–10.

Estimate from a set taken close to failure for the best accuracy.

Estimates for healthy adults. Not medical advice — talk to a qualified professional about your specific situation.

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Start with 2–3 full-body sessions per week, focus on a handful of basic movements, use a weight you can control with good technique, and add a little each week.

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Frequently asked questions

Is it safe to test my real 1RM?

For beginners an estimate is safer. Experienced lifters should test with a spotter and proper warm-up.

Why do formulas differ?

Each was fit to different data. Averaging reduces the error of any single formula.

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