One Rep Max Calculator

Estimate the maximum weight you can lift for a single rep from any submaximal set.

About this calculator

Your one-rep max (1RM) is the heaviest weight you can lift once with good form. Estimating it from a 3–8 rep set is safer than max testing and is the basis for percentage-based training programs.

Formula

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

Results are estimates for information only — not medical advice. Sources: WHO, CDC, and peer-reviewed research.