Calculator
One rep max calculator
Enter a recent hard set. You'll get your estimated one rep max and what to lift for any number of reps, without ever testing a true max.
Average of the Epley and Brzycki formulas. Most accurate from sets of 3 to 8 reps.
| Reps | % of max | Weight |
|---|
How it works
Your one rep max (1RM) is the most you could lift once. Testing it is tiring and risky, so it's usually estimated from a set of several reps:
- Epley: 1RM = weight × (1 + reps ÷ 30)
- Brzycki: 1RM = weight × 36 ÷ (37 − reps)
The two agree closely between 3 and 8 reps; above 12 they get unreliable, so the calculator stops there. Use the estimate to track progress over weeks and to pick training weights, not as a target to test.
Using it to plan sets
For strength, most of your work sits around 75–85% of your max for 5 to 8 reps. For muscle, 65–80% for 8 to 12 reps works well. Leave a rep or two in the tank either way, and add weight with double progression.
Your estimated max, tracked automatically
Recomp estimates your max for every main lift after each session and shows the line climbing, so you see progress without ever testing a single rep.
Get Recomp for iPhone