One Rep Max
Epley & Brzycki formulas
About This Calculator
One Rep Max (1RM) is the maximum weight you can lift for exactly one repetition with proper form. It is used to prescribe training loads as a percentage of 1RM. Since directly testing 1RM carries injury risk, sub-maximal formulas estimate it from lighter lifts performed for multiple reps.
Formula
Epley: 1RM = weight × (1 + reps/30)
Brzycki: 1RM = weight × 36 / (37 − reps)
Lombardi: 1RM = weight × reps^0.10
Use these formulas for 1-10 reps — accuracy decreases above 10 reps
Example Calculation
Bench press 80 kg for 6 reps
- Epley: 1RM = 80 × (1 + 6/30) = 80 × 1.20 = 96 kg
- Brzycki: 1RM = 80 × 36/(37−6) = 80 × 36/31 = 92.9 kg
- Average estimate: ~94 kg
Estimated 1RM: approximately 93-96 kg
% of 1RM by Rep Range (Training Guide)
| Reps | % of 1RM | Goal | RPE |
|---|---|---|---|
| 1 | 95-100% | Max strength test | 10 |
| 2-3 | 90-95% | Strength | 9-10 |
| 4-6 | 80-87% | Strength/power | 8-9 |
| 6-10 | 70-80% | Hypertrophy | 7-8 |
| 12-15 | 65-70% | Muscular endurance | 6-7 |
| 15-20+ | < 65% | Endurance | 5-6 |
Frequently Asked Questions
Which 1RM formula is most accurate?
Epley and Brzycki are most commonly used and perform similarly for moderate rep ranges (3-6 reps). Accuracy decreases above 10 reps. For best results, use a rep range closest to 1 (e.g., a 3RM test × 1.08 gives a good 1RM estimate).
How do I use 1RM for programming?
Most strength programs prescribe sets at a percentage of 1RM. 80% 1RM for 5 sets of 5 (5×5) builds strength. 70% for 3×10 targets hypertrophy. Programs like 5/3/1 and Texas Method use 1RM percentages to autoregulate training loads.
Should I test my actual 1RM?
For beginners, 1RM testing is unnecessary and carries injury risk. Use sub-maximal formulas. Intermediate and advanced lifters can test 1RM safely with a proper warm-up, a spotter (for barbell lifts), and good technique. Test no more than once per training cycle.
What is RPE?
Rate of Perceived Exertion (RPE) on a 1-10 scale where 10 = maximum effort (true 1RM). RPE 8 means you had 2 reps left in reserve. Modern strength programs increasingly use RPE instead of fixed percentages to account for daily variation in strength and recovery.