One rep max calculator

Estimate the most you could lift for a single rep, based on a heavier set you have already done.

Units
The load you used for the set.
Between 1 and 12. Estimates are most reliable up to about 10.
Estimated one rep max — kg

By method

Epley —
Brzycki —

Training percentages

Common percentages of your one rep max with the rep range each tends to allow.
% of 1RM Weight Typical reps

How this is calculated

Two well-established formulas estimate a one rep max from a sub-maximal set. The primary number is their average, rounded to the nearest 0.5 kg (metric) or 1 lb (imperial).

Epley: 1RM = weight x (1 + reps / 30)

Brzycki: 1RM = weight x 36 / (37 - reps)

At 1 rep the result is the weight itself. Both formulas drift apart as reps climb, which is why estimates above ~10 reps are less reliable.

Estimates only. Not medical advice. Talk to a clinician for personal guidance.