One Rep Max (1RM) Calculator

Estimate your one-rep max for any lift based on weight and reps. Get a training percentage chart for programming your workouts.

This calculator estimates the most weight you could lift for a single repetition from a submaximal set, using three published formulas side by side. The headline figure is the Epley estimate — weight times (1 + reps/30) — which grows linearly with reps: each additional rep adds one-thirtieth of the bar weight to the estimate. The Brzycki and Lander estimates are hyperbolic instead, dividing the weight by a shrinking factor, so they climb faster than Epley as reps rise and the three formulas diverge noticeably past ten reps. All three are pinned to agree when reps equal one — a true single just returns the weight lifted, so testing your actual 1RM needs no formula at all. Weight and reps do not pull equally: because every formula multiplies by the full weight, a ten percent change in Weight Lifted moves every estimate by ten percent, while a ten percent change in reps moves them by only about one to three percent in typical ranges. The training chart applies fixed percentages of the Epley estimate (95 percent for doubles, 85 for sets of five to six, and so on) for programming. These formulas assume reps to near-failure with good form; they say nothing about lift-specific skill, fatigue, or grip limits, and accuracy degrades beyond about ten reps.