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One Rep Max (1RM) Calculator

Estimate your one-rep max from a set of reps.

Last updated: 25 Aug 2026

Quick answer

The Epley formula estimates your one-rep max: 1RM = weight × (1 + reps ÷ 30). For example, 80 kg for 5 reps ≈ 93 kg. Enter the weight lifted and reps above.

Estimate your one-rep max (1RM) — the most you could lift once — from a lighter set, using the Epley formula: 1RM = weight × (1 + reps ÷ 30).

How to calculate your one-rep max

  1. 1 Enter the weight you lifted.
  2. 2 Enter the number of reps you completed.
  3. 3 We estimate your 1RM.

Frequently asked questions

What is one-rep max?
The maximum weight you can lift for a single repetition of an exercise.
Which formula is used?
The Epley formula: 1RM = weight × (1 + reps ÷ 30); it is most accurate for lower rep counts.
Should I test my true 1RM?
Estimating from a submaximal set is safer; test a true 1RM only with proper warm-up and a spotter.

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