How to calculate one rep max
1RM = Weight × (1 + Reps ÷ 30)
Worked example. Estimated one-rep max: 216 lb.
Example inputs — Weight lifted: 185 lb; Reps completed: 5. Starting values are illustrative.
From George Guju, founder of Calculyn · Educational calculator guidance, not professional advice.
How it works
Uses the Epley formula, which is most accurate for sets of 2–10 reps. Training percentages help plan working sets.
Assumptions & limitations
- Results are rounded for display.
Formula and assumptions reviewed October 2026 by the Calculyn team. How we build our calculators
Frequently asked questions
Should I test my true max?
Only with a spotter and good form. The estimate is a safer way to plan training.