Strength calculator
One-Rep Max Calculator
Frequently asked questions
- How do you calculate a one-rep max?
- Enter the weight and reps from a recent clean set. Epley uses weight × (1 + reps/30); Brzycki uses weight × 36/(37 − reps). Both are estimates, not a tested max.
- Which 1RM formula should I use?
- Epley and Brzycki are usually close on low-rep sets. The average of both is a practical default for programming. Prefer sets of about 10 reps or fewer for better estimates.
- Is a calculated 1RM the same as a tested max?
- No. Formulas assume clean reps and typical fatigue. Use the estimate for working percentages; do not treat it as a competition attempt.
How the formulas work
Epley uses 1RM = weight * (1 + reps / 30). Brzycki uses 1RM = weight * 36 / (37 - reps). Both are estimates, and they are generally more useful from lower-rep sets than very high-rep endurance sets.
Keep your inputs to clean reps with consistent form. If a set broke down or included forced reps, the estimate may be too high for programming.
Estimated 1RM
114.6 kg
Treat this as a training estimate, not a guarantee of what you should attempt under maximal load.
Epley
116.7 kg
Brzycki
112.5 kg
Average
114.6 kg
| Percent of 1RM | Weight |
|---|---|
| 95% | 108.9 kg |
| 90% | 103.1 kg |
| 85% | 97.4 kg |
| 80% | 91.7 kg |
| 75% | 85.9 kg |
| 70% | 80.2 kg |
| 65% | 74.5 kg |
| 60% | 68.8 kg |
| 55% | 63.0 kg |
| 50% | 57.3 kg |
Use your estimate with exercise guides
A 1RM estimate is most useful when paired with repeatable technique on the same lift. Start with these core tools and big-lift guides, then recalculate when your working sets improve.