One Rep Max Calculator
Estimate your 1RM using three proven formulas. Enter any weight and rep combination to see your max and a full rep-max table.
About 1RM Formulas
Brzycki Formula
1RM = weight × (36 / (37 - reps))
Developed by Matt Brzycki in 1993. Considered the most accurate for lower rep ranges (1-10). This is the formula used by StrengthMaxxer for strength scoring.
Epley Formula
1RM = weight × (1 + reps / 30)
The most widely used formula in programming. Linear relationship means it can over-estimate at very high rep ranges. Used by StrengthMaxxer for progression calculations.
Wendler Formula
1RM = weight × reps × 0.0333 + weight
Popularized by Jim Wendler's 5/3/1 program. Mathematically equivalent to the Epley formula but written differently. Commonly used for training max calculations.