One-rep max calculator
Enter a weight and the number of reps you completed with it, and we'll estimate your one-rep max along with a full chart showing what to lift for any rep target from 1 to 10.
How is this estimate calculated?
This calculator uses the Epley formula, one of the most widely used methods for estimating one-rep max from submaximal sets. For the most reliable estimate, use a set taken close to failure at 10 reps or fewer. The result is an estimate, not a guaranteed max: actual maxes vary by lift and by person, so don't attempt a true one-rep max based on it without solid technique, a spotter or safety arms, and some experience with heavy singles.
Sources: Epley B. Poundage Chart, Boyd Epley Workout, 1985 (original formula). LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD. "The Accuracy of Prediction Equations for Estimating 1-RM Performance in the Bench Press, Squat, and Deadlift." Journal of Strength and Conditioning Research, 1997 (compared several prediction formulas, including Epley, against tested maxes, and found accuracy varied between lifts).
Frequently asked questions
What is a one-rep max?
Your one-rep max, or 1RM, is the heaviest weight you can lift for a single complete repetition of an exercise with good form. It's a common reference point for programming training intensity.
How do you estimate 1RM without actually testing it?
This calculator uses the Epley formula, which estimates your one-rep max from a lighter set taken close to failure. It's most reliable with sets of roughly 10 reps or fewer, and the estimate drifts further from a real max as reps climb.
Why does the calculator only accept up to 12 reps?
Rep-max formulas lose accuracy as rep counts climb, since fatigue and endurance start to matter more than raw strength. The calculator accepts up to 12 reps, but a set of 10 or fewer gives a more reliable estimate.
What is the percentage table used for?
Once you know your estimated 1RM, the percentage table shows roughly how much weight to use for a target number of reps, which is useful for planning sets across a training block.