One Rep Max Calculator
An estimate of the heaviest single lift you could manage, with six formulas.
Enter the weight you lifted and how many reps you managed. The tool computes six published equations and builds a training percentage table from your chosen one.
This is an estimate, not an invitation to attempt it. If you do intend to test a true one-rep max, a full warm-up and a spotter are essential.
Fill in your details and press calculate — your result will appear here.
Formula and method
Six regression equations, all fitted on sets taken close to failure. Epley is the default.
Formula used
Six published 1RM prediction equations, Epley by default
Assumptions and limits
- Accuracy degrades sharply above about ten reps, and the tool flags that range.
- If your set stopped well short of failure, it is not a valid input for these formulas.
Scientific sources
Epley B. “Poundage Chart.” Boyd Epley Workout. University of Nebraska, Lincoln, 1985.
Brzycki M. “Strength testing: predicting a one-rep max from reps-to-fatigue.” JOPERD. 1993;64(1):88-90.
Lombardi VP. Beginning Weight Training. Wm. C. Brown, 1989.
Mayhew JL, Ball TE, Arnold MD, Bowen JC. “Relative muscular endurance performance as a predictor of bench press strength.” J Appl Sport Sci Res. 1992;6(4):200-206.
Wathan D. “Load assignment.” In: Baechle TR, ed. Essentials of Strength Training and Conditioning. Human Kinetics, 1994.