One Rep Max Calculator
How much could you lift for a single perfect rep? Enter a weight you lifted and the reps you managed with good form, and get your estimated one-rep max from three established formulas — plus a percentage chart for planning your training sets safely.
Enter your details above and the result will appear here.
How to use
- Enter the weight you lifted, in kilograms or pounds — the result is in the same unit.
- Enter the reps you completed with good form.
- Read the three estimates and the percentage chart.
Note
Epley: weight x (1 + reps/30). Brzycki: weight x 36 / (37 - reps). Lombardi: weight x reps^0.10. Estimates are most accurate under about 10 reps and vary by exercise — never test a true max without proper setup and spotters. Estimate only — not medical advice.
Tips
- Use a weight you lifted with strict form — sloppy reps inflate the estimate.
- Estimates are most reliable from sets of 10 reps or fewer.
- The percentage chart is for planning training sets, not for maxing out every week.
- Warm up properly before any heavy single — the calculator cannot do that part for you.