Estimate Without the Risk

Maxing out is the surest way to stall, and the easiest way to get hurt. The one-rep max calculator instead estimates your 1RM from a comfortable set of 2–12 reps, using four of the best-known prediction formulas.

The Formulas

Epley: w × (1 + r/30). Brzycki: w × 36/(37 − r). Lombardi: w × r^0.1. O'Conner: w × (1 + r/40). Each models how strength decays as reps rise; they agree closely at low reps and drift apart as reps climb — so the average is the sensible working number.

Train with Percentages

Programs prescribe loads as percentages of 1RM: 55–65% for volume, 70–80% for hypertrophy, 85–95% for strength. The max table converts your estimate into actual working weights across the 1–12 rep spectrum.