How to Calculate Your One Rep Max (1RM)
Your one-rep max (1RM) is the maximum weight you can lift for a single repetition with good form. It is the foundation of strength programming — used to set training percentages, track progress, and compare yourself to strength standards. You do not need to actually attempt a max lift to calculate it.
The Most Accurate 1RM Formulas
| Formula | Equation | Best For |
|---|---|---|
| Epley | 1RM = weight × (1 + reps / 30) | General use, 1–10 reps |
| Brzycki | 1RM = weight / (1.0278 − 0.0278 × reps) | Lower rep ranges (1–8) |
| Lander | 1RM = (100 × weight) / (101.3 − 2.67123 × reps) | General use |
| Lombardi | 1RM = weight × reps^0.10 | Higher rep ranges |
All formulas become less accurate above 10 reps. For most accurate estimation, use a weight you can lift for 3–8 reps performed to near-failure.
Training Percentages from Your 1RM
| %1RM | Reps Possible | Training Effect |
|---|---|---|
| 95% | 1–2 reps | Peak strength, neural adaptation |
| 85–90% | 2–4 reps | Strength + some hypertrophy |
| 75–85% | 5–8 reps | Strength-hypertrophy continuum |
| 65–75% | 8–15 reps | Primary hypertrophy zone |
| 50–65% | 15–30 reps | Muscular endurance, metabolic stress |
Should You Ever Actually Test Your 1RM?
Calculated 1RM is sufficient for programming purposes. However, actual max testing has its place — competition preparation, annual benchmarking, or peak programmes where you want to verify your training is transferring to the barbell. If you test, do it after a proper warm-up, on a day with full recovery, with a spotter or safety equipment.
💡 The average estimation error of 1RM formulas is 5–10%. Use your calculated 1RM as an approximation — always listen to how the weight feels and adjust accordingly.
Calculate Your 1RM Instantly
Enter any weight + reps combination and see your estimated 1RM across multiple formulas, plus training percentages.
Use the One Rep Max Calculator →