One Rep Max (Brzycki) Calculator

About this calculator

The Brzycki formula — 1RM = weight ÷ (1.0278 − 0.0278 × reps) — estimates the maximum weight you could lift for a single repetition based on a lighter weight lifted for multiple reps, published by strength coach Matt Brzycki in a 1993 issue of the Journal of Physical Education, Recreation and Dance. It assumes a fairly linear relationship between reps performed and percentage of true 1RM, which holds reasonably well in the roughly 2-to-10-rep range but grows less accurate at very high rep counts.

Strength coaches and lifters use rep-max formulas like Brzycki's — alongside competing versions such as the Epley formula — to estimate a 1RM without the injury risk and fatigue cost of actually testing a maximal single lift, which is useful for programming training percentages (like setting a working weight at 75% of estimated 1RM) and tracking strength progress between true max-out sessions.

This calculator takes the weight you lifted and the number of reps performed and returns your estimated one-rep max using the Brzycki formula.