# One-rep max calculator: estimate your 1RM and training percentages

Your one-rep max (1RM) is the most you can lift once with good form. You can estimate it from a harder set of a few reps instead of testing it: Epley uses weight × (1 + reps ÷ 30) and Brzycki uses weight × 36 ÷ (37 − reps). Estimates are best from sets of 10 reps or fewer.

## How it works

### Two formulas

Epley and Brzycki agree closely below 10 reps and drift apart above it. The calculator shows both and their average.

### Percentages

Strength work is often planned at 75% to 90% of 1RM and hypertrophy work at 65% to 80%. The table rounds to the nearest 2.5.

## Questions

### Is it safe to test a true 1RM?

It carries more risk than an estimate, especially without a spotter or experience. An estimate from a set of 3 to 6 reps is enough for planning.

### Why do the formulas give different numbers?

They were fitted to different groups and lifts. Use one consistently so your progress compares like with like.

### Does it work for bodyweight exercises?

Add your bodyweight to the load for exercises like pull-ups and dips, then subtract it from the result.

Accurate as of November 12, 2026.

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