One Rep Max Calculator App
Enter a weight and the reps you managed. Get an estimated one rep max, plus the full percentage table you actually train off.
- Estimate a 1RM from any weight and rep count
- Compare Epley, Brzycki, and other formulas side by side
- Full percentage table for programming working sets
- Save lifts and watch estimates change over time
- Plate breakdown for each percentage
Why estimate instead of test
Testing a true one rep max is taxing, needs a spotter, and is only accurate on the day you do it. A set of five taken close to failure gives you a number that is nearly as useful and costs you nothing. Most programs are written in percentages of that number.
Formulas disagree, so see them all
Epley and Brzycki can differ by several percent, and the gap widens as reps go up. Rather than pick one silently, the app shows the spread so you can judge. Below about six reps they converge closely; above ten, treat any estimate as a rough guide.
Common questions
How many reps should I use for the best estimate?
Between three and six, taken close to failure. Higher rep sets drift further from reality because fatigue and conditioning start dominating.
Which formula is most accurate?
None is universally best. Epley tends to read slightly higher at high reps, Brzycki slightly lower. Pick one and stay consistent so your numbers are comparable over time.