One-Rep Max Calculator

Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition, with full effort and correct technique. Measuring it directly is risky and fatiguing, so it's usually estimated from a set of several reps taken close to failure, using the Epley formula: 1RM = weight lifted × (1 + reps / 30).

This formula works best for sets under 10 reps; beyond that, accuracy drops because muscular endurance plays a bigger role than raw strength. Your 1RM is then used as a reference to program training intensity — for example, training at 70-80% of your 1RM for strength, or 60-70% for muscle hypertrophy.