One Rep Max Calculator

Calculate your theoretical 1RM using the most proven formulas in strength training.

Lifted Weight

kg/lbs

Reps Performed

Average

Most balanced

261 kg/lbs

Epley

Powerlifting standard

263 kg/lbs

Brzycki

Best for low reps

253 kg/lbs

Lombardi

Best for high reps

264 kg/lbs

Wathen

Highest accuracy

262 kg/lbs

Formula Comparison

Estimated 1RM if you lift 100 kg/lbs for different reps.

Reps	Average	Epley	Brzycki	Lombardi	Wathen
100 × 1	100	100	100	100	100
100 × 2	105	107	103	107	105
100 × 3	109	110	106	112	109
100 × 4	113	113	109	115	113
100 × 5	116	117	113	117	117
100 × 6	119	120	116	120	120
100 × 7	122	123	120	121	124
100 × 8	125	127	124	123	128
100 × 9	129	130	129	125	131
100 × 10	132	133	133	126	135

How it works

Your One Rep Max (1RM) is the maximum amount of weight you can lift for a single repetition. Since testing a true 1RM can be dangerous and taxing on the central nervous system, lifters use formulas to estimate it based on sub-maximal sets.

The Formulas

Epley: The standard for powerlifting. Tends to be slightly optimistic for high reps but very accurate for low reps (1-5).
Brzycki: Often considered the most accurate for reps between 6-10. Widely used in collegiate strength programs.
Lombardi: Uses an exponential curve. Good for general strength estimation but can vary at extremes.
Wathen: A more complex formula designed to be consistent across a wider range of rep schemes.

Track your PRs automatically

Plates calculates your 1RM for every exercise, every workout. No calculator needed.