1RM calculator guide
Estimate your one-rep max from a multi-rep set using the Epley and Brzycki formulas — without testing a true max.
1 min read
Written & reviewed by Ricardo Tapia·Last updated
The 1RM calculator estimates your one-rep max (1RM) — the most you could lift once — from a weight you lifted for several reps. Handy for setting working weights without testing a true max.
Two formulas
Epley: 1RM = weight × (1 + reps ÷ 30)
Brzycki: 1RM = weight × 36 ÷ (37 − reps) # best under ~10 reps
Accuracy drops above ~10 reps — use a set of 3–6 reps for the best estimate.
Try it
Estimate your max in the 1RM calculator.
Sources & references
- Brzycki M. Strength testing—predicting a one-rep max from reps-to-fatigue. JOPERD. 1993;64(1):88-90.
- Epley B. Poundage chart. Boyd Epley Workout. Lincoln, NE; 1985.
Educational content only. Not medical advice — consult a professional for your situation.