One Rep Max Calculator (1RM)

Weight lifted Reps completed (1-12)

Estimated 1RM (average)-

Epley-

Brzycki-

Lombardi-

Training weights by percent of your 1RM

% of 1RM	Weight	Approx. reps

How it works

Your one rep max is the heaviest weight you could lift once with good form. Testing it directly is tiring and risky, so these formulas estimate it from a lighter set taken close to failure. Epley: weight × (1 + reps ÷ 30). Brzycki: weight × 36 ÷ (37 − reps). Lombardi: weight × reps^0.10. The headline number is the average of the three. Estimates are most accurate for sets of 2 to 10 reps and drift for higher counts.

Example: 185 lb for 5 reps gives Epley 216, Brzycki 208 and Lombardi 217, so an average 1RM of about 214 lb.

FAQ

Which formula is best?

None is exact, since people fatigue differently. Epley tends to run a bit higher and Brzycki a bit lower on moderate reps; the average is a sensible middle.

Does it work for kg?

Yes. The formulas only scale the number you enter, so results come back in the same unit (lb or kg).

Is it safe to lift my estimated 1RM?

Treat it as a planning number for choosing working weights, not as a target for today. Attempt true maxes only with a spotter and a proper warm-up.