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.
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 accurate for sets of roughly 10 reps or fewer, and less reliable beyond that.
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. Keeping the input under 12 reps keeps the estimate reasonably reliable.
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.