One-Rep Max Calculator
Estimate your 1RM for bench, squat, deadlift, and overhead press using 7 prediction formulas (Epley, Brzycki, Lombardi, Mayhew, Wathan, Lander, O'Conner) with training load tables and strength classification
Lift Performed
Until form failure (max 12 reps for accuracy)
Quick presets
Estimates by Formula
| Formula | 1RM (kg) | Equation |
|---|---|---|
| Epley | 116.7 | 1RM = w × (1 + r/30) |
| Brzycki | 112.5 | 1RM = w × 36 / (37 − r) |
| Lombardi | 117.5 | 1RM = w × r^0.10 |
| O'Conner | 112.5 | 1RM = w × (1 + 0.025r) |
| Mayhew | 119.0 | 1RM = 100w / (52.2 + 41.9·e^(−0.055r)) |
| Wathan | 116.6 | 1RM = 100w / (48.8 + 53.8·e^(−0.075r)) |
| Lander | 113.7 | 1RM = 100w / (101.3 − 2.67123r) |
Training Loads (% of 1RM)
Use these working weights for the corresponding rep ranges in your program.
| Reps | % 1RM | Weight (kg) | Notes |
|---|---|---|---|
| 1 | 100% | 115.5 | Max effort |
| 2 | 95% | 109.7 | RPE 9.5 |
| 3 | 93% | 107.4 | RPE 9 |
| 4 | 90% | 103.9 | |
| 5 | 87% | 100.5 | 5×5 working set |
| 6 | 85% | 98.2 | |
| 7 | 83% | 95.9 | |
| 8 | 80% | 92.4 | Hypertrophy zone |
| 9 | 77% | 88.9 | |
| 10 | 75% | 86.6 | |
| 11 | 72% | 83.2 | |
| 12 | 70% | 80.8 | Endurance/tempo |
| 15 | 65% | 75.1 | |
| 20 | 60% | 69.3 |
Bench Press Strength Standards (male)
Approximate 1RM benchmarks for an adult lifter at average bodyweight (~80 kg male / 65 kg female).
About 1RM Estimation
Your One-Rep Max (1RM) is the heaviest weight you can lift for a single repetition with proper form. Testing a true 1RM is risky and tiring, so most lifters estimate it from a sub-maximal set using prediction formulas.
- Best accuracy with 1–5 reps. Estimates degrade above 10 reps because muscular endurance becomes the limiter, not pure strength.
- Epley and Brzycki are the most cited; results above usually agree within ±5%.
- Mayhew and Wathan were derived from bench-press data and are most accurate for that lift.
- Lander over-predicts past 10 reps and breaks down at 38+ reps (denominator → 0).
- Strength standards based on Symmetric Strength / ExRx aggregated norms; bodyweight, training history, and lift technique heavily influence what's achievable.
Educational tool. Always lift with a spotter or in a power rack when attempting near-maximal weights. Consult a qualified coach for programming.
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