One Rep Max Calculator
Estimate your one-rep max from a submaximal lift using seven proven formulas. View a full % of 1RM training table and switch between kg and lb instantly.
Estimated 1RM
115.5 kg
Average of 7 formulas
Per-formula breakdown
| Formula | Estimated 1RM (kg) |
|---|---|
| Epley | 116.7 |
| Brzycki | 112.5 |
| Lander | 113.7 |
| Lombardi | 117.5 |
| Mayhew | 119 |
| O’Conner | 112.5 |
| Wathan | 116.6 |
| Average | 115.5 |
Percentage of 1RM training table
| % of 1RM | Weight (kg) | Typical reps |
|---|---|---|
| 100% | 115.5 | 1 |
| 95% | 109.5 | 2 |
| 90% | 104 | 4 |
| 85% | 98 | 6 |
| 80% | 92.5 | 8 |
| 75% | 86.5 | 10 |
| 70% | 81 | 12 |
| 65% | 75 | 14 |
| 60% | 69.5 | 16 |
| 55% | 63.5 | 18 |
| 50% | 58 | 20 |
What is one-rep max?
Your one-rep max (1RM) is the heaviest weight you can lift with proper form for a single repetition of an exercise. It is the gold-standard expression of absolute strength for compound lifts like the squat, bench press, deadlift, and overhead press.
True 1RM testing is fatiguing and carries injury risk, so most programs estimate 1RM from a submaximal lift — for example, the most weight you can lift cleanly for 5 reps. A calculator extrapolates that result to a one-rep equivalent so you can prescribe training loads as a percentage of 1RM without ever grinding out a true max.
Formula comparison
Seven widely cited equations are included. They agree closely at low rep counts (1–5) and diverge as reps climb. Averaging multiple formulas usually gives the most balanced estimate.
| Formula | Equation | Best for |
|---|---|---|
| Epley | w * (1 + r / 30) | Most popular; best 1-10 reps |
| Brzycki | w * 36 / (37 - r) | Conservative, ≤10 reps |
| Lander | (100 * w) / (101.3 - 2.67123 * r) | Linear, low reps |
| Lombardi | w * r^0.10 | Power-law, high-rep tolerant |
| Mayhew | (100 * w) / (52.2 + 41.9 * e^(-0.055 * r)) | Bench press research-derived |
| O’Conner | w * (1 + 0.025 * r) | Quick mental math |
| Wathan | (100 * w) / (48.8 + 53.8 * e^(-0.075 * r)) | Validated across many lifters |
Rep range goals
Your training goal determines how many reps to perform at a given percentage of 1RM. Use these ranges as a programming starting point.
- Strength: 1–5 reps at 85–100% 1RM. Long rests (3–5 min). Builds maximal force production and neural drive.
- Hypertrophy: 6–12 reps at 67–85% 1RM. Moderate rests (60–120 s). The classic muscle-building zone.
- Muscular endurance: 13–20 reps at 50–67% 1RM. Short rests (30–60 s). Improves work capacity and local endurance.
- Power: 1–5 reps at 30–60% 1RM, moved explosively. Full recovery between sets. Trains rate of force development.
Safety
Don’t test true 1RM without a spotter, proper warm-up, and at least 12 weeks of consistent training. Calculators are a safer alternative for programming.