1-Rep Max Calculator
Estimate your one-rep max from a weight and rep count you can already do.
Last updated
Educational estimate, not coaching advice. These formulas are approximations that get less accurate above about 10 reps — actual 1RM varies by lift, technique, and fatigue. Always use proper form and a spotter for max attempts. See our terms for details.
—Epley formula
—Brzycki formula
—Average estimate
Enter a weight and rep count above.
The formulas
Epley: 1RM = weight × (1 + reps ÷ 30). Brzycki: 1RM = weight × 36 ÷ (37 − reps) — this one is undefined at 37 reps and unreliable well before that, so treat any high-rep estimate from either formula as a rough ballpark rather than a number to load on the bar.
Nothing entered here is sent to a server — the entire calculation runs as JavaScript in your browser tab.