The Epley formula estimates your one-rep max from a submaximal weight and rep count: 1RM = weight x (1 + reps / 30). It is widely used because it is simple and works well for compound lifts.
The Epley equation
1RM = weight x (1 + reps / 30)
Example: if you lift 100 kg for 5 reps, your estimated 1RM is 100 x (1 + 5 / 30) = 116.7 kg. The formula assumes a roughly linear relationship between load and reps for compound lifts.
When the Epley formula is most accurate
- Compound lifts: Squat, bench press, deadlift, and overhead press respond well to the formula.
- 2-10 reps: The sweet spot is roughly 2-6 reps; up to 10 is still reasonable.
- Trained lifters: Experienced athletes with consistent technique get more reliable estimates.
When it may overestimate or underestimate
- High-rep sets: Above 12 reps, fatigue and endurance blur the linearity assumption.
- Beginners: Neuromuscular inexperience means technique and efficiency vary widely.
- Isolation movements: Bicep curls or triceps extensions do not follow the same load-rep pattern.
Comparison with other 1RM formulas
| Formula | Equation | Notes |
|---|---|---|
| Epley | w x (1 + r/30) | Simple; best for 2-10 reps |
| Brzycki | w x 36 / (37 - r) | More conservative; popular with coaches |
| Lombardi | w x r^0.10 | Aggressive; power athletes |
| Mayhew | (100 x w) / (52.2 + 41.9 x e^(-0.055 x r)) | Complex; body-weight scaled |
Practical training use
Once you have an estimated 1RM, you can set loads by percentage: strength at 80-90% for 3-5 reps, hypertrophy at 65-75% for 8-12 reps, and endurance at 50-65% for 12-15+ reps. Pair this with the macro calculator and protein calculator to support recovery.
Sources and further reading
These independent, authoritative sources inform the methods used on this page.