How to calculate your 1RM without maxing out (Epley formula)
Short answer: Your one-rep max (1RM) is the most weight you can lift once. You can estimate it from a normal set with the Epley formula: 1RM = weight × (1 + reps / 30). For example, 80 kg for 8 reps gives 80 × (1 + 8/30) ≈ 101 kg.
Worked examples
- 100 kg × 5 reps → 100 × 1.167 ≈ 117 kg
- 60 kg × 10 reps → 60 × 1.333 = 80 kg
- 135 lb × 12 reps → 135 × 1.4 = 189 lb
How accurate is it?
Estimates are closest for sets of about 1 to 10 reps taken close to failure. Above 10 to 12 reps they drift, and they vary by exercise and person. Treat the number as a trend line, not a promise of what you can lift today. The Brzycki formula (weight × 36 / (37 − reps)) gives similar results at low reps.
Why track estimated 1RM
Your sets change from week to week: 5 reps one day, 8 the next. Converting each set to an estimated 1RM puts them on one scale, so you can see whether you are actually getting stronger without testing a true max, which carries more injury risk.
In Repsheet
Repsheet calculates estimated 1RM with the Epley formula for every set you log and charts the best value per session for each exercise, next to top weight and volume, with PR badges when you set a record. Free, all exercises unlocked, offline.