How we estimate your one-rep max
No single 1RM prediction formula is universally most accurate. Research shows accuracy depends on the exercise, your training experience, rep range used, and individual variation.
By averaging three well-validated formulas, we reduce the error from any single formula's bias and provide a more robust estimate.
The most widely used formula. Simple, linear, and well-validated across general populations. Developed by Boyd Epley at the University of Nebraska.
Particularly accurate when reps are 10 or fewer. NCAA-validated and preferred in research settings for its conservative estimates. At exactly 10 reps, Brzycki and Epley give identical results.
Uses an exponential model that showed the lowest average error across multiple exercises in research. Validated across diverse populations including trained and untrained individuals.
Power-based model. Research showed it was the most accurate for men on bench press and squat specifically. Handles higher rep ranges better than linear formulas.
Recommended by the NSCA (National Strength and Conditioning Association). Particularly accurate for explosive athletes and powerlifters at low rep ranges.
All formulas become significantly less accurate above 10 reps. This is the most consistent finding across the research literature. Higher reps introduce more variables like muscular endurance and fatigue tolerance that aren't captured by these models.
Even with optimal conditions (trained athlete, compound lift, ≤10 reps), expect estimates to be within 2-5% of your true 1RM. For beginners or isolation exercises, error may be higher.
Research shows formulas tend to underestimate deadlift 1RM specifically. The formulas were primarily validated on bench press and squat.