One-Rep Max (1RM) Estimator
Calculate your maximum single-rep strength from any submaximal set. Compares the 6 peer-reviewed sports science formulas with an instant 50%–100% training load ledger.
50% – 100% Training Load Matrix
Pre-computed target weights for programming and percentage-based waves| Intensity | Estimated Reps | Training Focus | Target Weight |
|---|---|---|---|
| 100% | 1 Rep Max | Maximal Strength / Competition | 117.5 kg |
| 95% | 1 - 2 Reps | Heavy Peaking Singles | 110 kg |
| 90% | 2 - 4 Reps | Near-Maximal Neural Drive | 105 kg |
| 85% | 4 - 6 Reps | Strength Wave Progression | 100 kg |
| 80% | 6 - 8 Reps | Hypertrophic Strength Foundation | 92.5 kg |
| 75% | 8 - 10 Reps | Volume Hypertrophy | 87.5 kg |
| 70% | 10 - 12 Reps | Hypertrophy & Work Capacity | 82.5 kg |
| 65% | 12 - 15 Reps | Strength Endurance | 75 kg |
| 60% | 15+ Reps | Dynamic Effort / Speed Wave | 70 kg |
| 50% | Recovery | Warmup & Active Deload | 57.5 kg |
Scientific Formula Comparison
10 validated sports-science formulas evaluated against your lift| Formula | Citation | Calculated 1RM | Spread vs Avg |
|---|---|---|---|
Epley Formula (1985) | Boyd Epley (1985) | 116.7 kg | +2.2% |
Brzycki Formula (1993) | Matt Brzycki (1993) | 112.5 kg | -1.5% |
Lombardi Formula (1989) | V. P. Lombardi (1989) | 117.5 kg | +2.9% |
Wathen Formula (1994) | Denny Wathen (1994) | 116.6 kg | +2.1% |
Mayhew et al. (1992) | Jerry L. Mayhew et al. (1992) | 119 kg | +4.2% |
O'Conner et al. (1989) | O'Conner, Simmons & O'Shea (1989) | 112.5 kg | -1.5% |
Lander Formula (1985) | J. Lander (1985) | 113.7 kg | -0.5% |
Berger Exponential (1961/1962) | Richard A. Berger (1961) | 111.1 kg | -2.7% |
Reynolds et al. Nonlinear (2006) | Jeff M. Reynolds et al. (2006) | 114.8 kg | +0.5% |
Kemmler et al. Cubic (2006) | Wolfgang Kemmler et al. (2006) | 108 kg | -5.5% |
One-Rep Max Calculation Science & FAQs
Which 1RM formula is the most accurate?
The Epley and Brzycki equations are the gold standards for heavy barbell lifts under 10 repetitions. Brzycki is slightly more conservative, making it ideal for injury prevention and powerlifting meet attempts, while Epley is popular for bench press and squat programming.
Why does accuracy decline over 10 repetitions?
Extrapolating a 1RM from sets of 12–15+ reps introduces muscle fiber type variance, lactic acid buffering, and cardiovascular endurance factors that diminish maximal neurological force output.
How does RPE (Rating of Perceived Exertion) affect the calculation?
If you complete 5 reps at RPE 8, you had 2 reps in reserve (RIR). The calculator automatically normalizes your performance to an effective 7-rep max effort, ensuring you do not underestimate your peak capability.
How should I test a true 1RM in the gym?
Warm up thoroughly through 50%, 70%, 80%, and 90% singles before attempting 100%. Ensure full safety spotters and equipment before attempting true maximal lifts.