Prime Progression
1RM Calculator
Estimate your one-rep max from any weight × reps combination. Compares Epley, Brzycki, and Lander formulas.
Epley is the most common formula. Estimates work best for 1–10 reps.
| %1RM | Weight | ~Reps |
|---|---|---|
| 100% | 117 kg | 1 |
| 95% | 111 kg | 2 |
| 90% | 105 kg | 3 |
| 85% | 99 kg | 5 |
| 80% | 94 kg | 6 |
| 75% | 88 kg | 8 |
| 70% | 82 kg | 10 |
| 65% | 76 kg | 12 |
| 60% | 70 kg | 15 |
| 55% | 64 kg | 18 |
| 50% | 59 kg | 20 |
Prime Progression tracks your 1RM automatically across 100+ exercises.
Get Prime ProgressionFrequently asked questions about 1RM
How accurate is the 1RM calculator?
For sets of 1-6 reps, 1RM estimates are typically within 5% of your true max. Accuracy decreases as rep count increases because fatigue, technique breakdown, and cardiovascular limitations introduce more variability.
Which formula should I use?
Epley and Brzycki produce nearly identical results for low rep ranges. Brzycki tends to be slightly more conservative at higher reps. If you are unsure, Epley is the most widely used and a safe default.
How many reps is too many for an accurate estimate?
Estimates based on more than 10 reps become increasingly unreliable. Above 12 reps, muscular endurance and cardiovascular fitness dominate, and the result may overestimate your true one-rep max by 10% or more.