Estimate your 1RM from any set of reps using the most trusted strength formulas — then see your full training percentage table.
| Formula | Equation | Best for |
|---|---|---|
| Epley | w × (1 + r/30) | General use, widely cited |
| Brzycki | w × 36 / (37 − r) | Low rep sets (1–10 reps) |
| Lander | (100 × w) / (101.3 − 2.67 × r) | Consistent across rep ranges |
| Lombardi | w × r^0.10 | Higher rep sets |
w = weight lifted, r = reps performed. All formulas return weight itself when r = 1.
Your One Rep Max (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise with proper form. It is the universal standard for measuring absolute strength. Knowing your 1RM lets you programme training loads as precise percentages — for example, sets of 5 at 80% or sets of 12 at 65% — rather than arbitrary weights.
Tracking your 1RM over time is one of the clearest indicators of strength progress. It also lets you set training zones: heavier loads (85–100%) build maximum strength, moderate loads (70–85%) build strength and muscle size, and lighter loads (60–70%) improve muscular endurance. Without a 1RM reference point it is difficult to ensure progressive overload in your programme.
Estimation formulas are most accurate for sets of 1–10 reps. Accuracy decreases as reps rise above 10 because the limiting factor shifts from strength to muscular endurance, and individuals vary in their endurance capacity. The Epley and Brzycki formulas are most widely validated for compound lifts (squat, bench press, deadlift). For best results, use a weight that takes you close to failure at 3–8 reps and choose "Average of all formulas" to smooth out individual variation.
Testing a true 1RM carries a higher injury risk than sub-maximal testing, especially for beginners or on technically demanding movements like Olympic lifts. It requires a thorough warm-up, a competent spotter, and solid technique under heavy load. For most people, using this calculator with a challenging set of 3–5 reps is a safer and surprisingly accurate alternative. Always consult a qualified coach or trainer before attempting a true 1RM attempt.
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