One Rep Max Calculator
Calculate your 1RM for any lift and get a full percentage-based training chart — no need to max out.
For best accuracy, use a set of 3–8 reps at a challenging weight. Estimates become less accurate beyond 10 reps.
How to use your 1RM
Your estimated 1RM is the foundation of percentage-based training (PBT), used in powerlifting programs like 5/3/1, Sheiko, and GZCLP. Rather than maxing out (which is fatiguing and risky), you test a heavy set of 3–8 reps and estimate your max from there.
The percentage chart below your result shows how much to load for different rep ranges and training intensities. For example, working at 80% of your 1RM for sets of 5 is a common strength-building zone.
1RM calculator — FAQ
No single formula is best for everyone — accuracy varies by individual. The Epley formula tends to perform well across a wide range of lifters. Brzycki is often more accurate for lower rep ranges (1–6 reps). Using the average across multiple formulas gives a more robust estimate. The key variable is rep count: estimates from 3–6 reps are far more accurate than estimates from 10+ reps.
Not without proper preparation. A true 1RM attempt requires a thorough warm-up, a spotter for upper body lifts, and ideally experience with heavy singles. For most gym-goers, working at 85–95% of estimated 1RM for 2–3 reps is safer and nearly as effective for strength development. Save true max attempts for competition or carefully planned peaking cycles.