1RM Calculator

Every one-rep max formula turns a set you actually did into an estimate of the single heaviest rep you could do. Auto — the default — uses Epley for 1–6 reps and Brzycki for 7–30, because each is closest to reality in that range. You can pick either by hand instead.

Estimates are most reliable at 1–10 reps. Past that, small differences in pacing and fatigue swing the answer a long way, and past 30 reps the formulas stop being usable at all — that is why this page asks for a set between 1 and 30 reps rather than printing a number it does not believe.

Using the percentages. For strength work, 85–90 % of your 1RM for 3–5 reps. For hypertrophy, 70–80 % for 8–12 reps. The chart rounds to whole units, so load the nearest jump your plates allow.

These are estimates, not a test. Your real 1RM moves with fatigue, technique, sleep and how recently you have trained the lift. Treat the number as a starting point for programming, not a personal record.

Auto now uses Epley below 7 reps, so a 5-rep set reads a little higher here than it did before — an 80 kg × 5 set estimates 93.3 kg rather than 90.0 kg. Pick Brzycki to see the older number.