Free fitness tool

One-Rep Max Calculator

Estimate 1RM and useful training percentages.

Estimate your one-rep max with the Epley formula: weight × (1 + reps ÷ 30). It's most accurate for sets of 10 reps or fewer.

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How this calculator works

The Epley equation estimates one-rep max from a submaximal set.

How to use your result

Keep your inputs consistent and compare weekly trends. Make small changes only after enough data accumulates.

Important limitation

Calculator results are estimates. Pregnancy, eating disorders, medical conditions, injuries, or concerning symptoms require qualified professional guidance.

Frequently asked questions

How do I calculate my one-rep max?

Use the Epley formula — multiply the weight you lifted by (1 + reps/30). For example, 100 kg for 5 reps estimates about 117 kg.

Is it safe to test a true 1RM?

Only with experience, a proper warm-up, and safety setup (rack, spotter). Estimating from a submaximal set is safer for most lifters.

Turn these numbers into a plan

RizzFit builds your workouts, calories, and macros around your goal — and adapts as you progress.

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