How it works
We estimate your max three ways and show the average:
- NSCA chart: weight divided by the percentage the NSCA training load chart gives for your reps (for example 87% for 5 reps).
- Epley: weight x (1 + reps / 30).
- Brzycki: weight x 36 / (37 minus reps).
Epley and Brzycki give the same answer at 10 reps; below 10, Epley comes out a little higher. Estimates are most useful from sets of 10 reps or fewer, done with good form.
Safety
Use a spotter or safety arms for heavy sets of bench press and squat. An estimate is a guide for picking training weights, not a reason to test a true max without supervision.
Sources: NSCA, "Training Load Chart" (percent of 1RM by repetitions); Epley (1985) and Brzycki one-rep max equations, as summarized in "One-repetition maximum" (Wikipedia).