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One Rep Max (1RM) Calculator

Enter the weight you lifted and the number of reps; using the Epley formula we estimate your one-rep max (1RM) and your 90%, 80% and 70% training loads.

Estimated with the Epley formula: 1RM = weight × (1 + reps/30). Actual max varies by individual.

How to use

  1. Enter your values in the fields above.
  2. Press Calculate to see your result instantly.
  3. Use the Share button to copy a link to your result.

About this calculator

This calculator estimates the maximum weight you could lift for a single repetition — your one-rep max (1RM) — from the weight and rep count of a set you actually completed, using the Epley formula. Since testing a true 1RM directly carries injury risk, especially for lifts like the bench press or squat, lifters instead lift a submaximal weight for several reps and let the formula extrapolate the theoretical max.

Strength trainers use the result to program percentage-based training, where a set is prescribed as, say, 80% of 1RM rather than a fixed number of kilograms; the calculator also outputs 90%, 80% and 70% loads directly so a lifting program's target weights can be set without extra math.

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