One rep max calculator

How the calculator works

A one-rep max (1RM) is the heaviest weight you can lift for a single rep. Testing it directly is risky and exhausting, so these formulas estimate it from a lighter set you have already done. Epley — weight × (1 + reps ÷ 30) — suits lower reps best. Brzycki — weight × 36 ÷ (37 − reps) — is reliable in the 1–10 rep range. Lombardi — weight × reps to the power of 0.1 — holds up well at higher reps. Enter a recent set and the calculator returns all three plus their average. Use the percentage table below the average to pick working weights: warm-ups around 60%, back-off work near 80%, and a top single at 90% or more. Treat every estimate as a starting point, not a promise.