UNDERSTAND THE METHOD
How to use this calculator
Enter the load and the number of completed repetitions. Compare the seven equations. The summary averages Epley, Brzycki, and Wathen. The percentage table is arithmetic based on that summary; it does not account for your exercise, fatigue, technique, or training history.
What the result can tell you
These equations predict a one-repetition maximum from a submaximal set. Agreement between formulas is not a confidence interval. Do not attempt a maximum lift simply to check an estimate. Higher repetition counts generally add uncertainty.
Common questions
What is the one-rep max summary based on?
The calculator compares seven equations. Its summary averages the Epley, Brzycki, and Wathen estimates, and the percentage table uses arithmetic based on that summary.
Should I attempt a maximum lift to check the estimate?
No. The equations predict a one-repetition maximum from a submaximal set. Higher repetition counts add uncertainty, and agreement between formulas is not a confidence interval.
Sources & limitations
Sources checked September 12, 2026. These notes identify methods and assumptions. They have not received an independent clinical review.
- Brzycki describes a submaximal-repetition strength prediction equation.doi.org
- LeSuer and colleagues compare seven prediction equations.doi.org
- Reynolds and colleagues examine strength predictions from repetition tests.pubmed.ncbi.nlm.nih.gov