One Rep Max Calculator
Estimated one-rep max (1RM) using the Epley formula.
Formula: Epley: 1RM = weight × (1 + reps/30)
Worth Knowing
The Epley formula estimates the maximum weight you could lift once from a lighter weight lifted for several reps, which is far safer than actually attempting a true one-rep max. Accuracy is best in the low-rep range — roughly 2 to 10 reps — and degrades as reps climb, because high-rep sets are limited as much by fatigue and cardiovascular factors as by pure strength. Different formulas (Brzycki, Lombardi) give slightly different numbers, so use one consistently to track progress.
How to Use
- Enter Weight lifted into the first field of the One Rep Max Calculator.
- Fill in the rest: Repetitions.
- Your result appears instantly as you type — there's no submit button or page reload.
Formula
Epley: 1RM = weight × (1 + reps/30)