1-Rep Max Calculator
Estimate the most weight you could lift for a single rep.
Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition of an exercise. It's the benchmark strength coaches use to set training loads, track progress, and program effectively.
Testing a true 1RM can be risky, so this calculator estimates it from a set you've already done using the Epley formula. Enter the weight you lifted and the reps you achieved, and we'll predict your max along with percentage-based training loads.
This is an estimate to guide your training — not a substitute for proper coaching. Always warm up, use good technique, and train within your limits.
Calculate your 1RM
How the calculation works
This calculator uses the Epley formula, one of the most widely used equations for estimating a one-rep max from a submaximal set. It works best for sets in the 2–10 rep range — accuracy drops as the rep count gets very high.
Epley formula (1RM):
1RM = (weight kg × reps × 0.0333) + weight kg
Once you know your estimated 1RM, you can program your training around percentages of that number. Heavier percentages build maximal strength with fewer reps, while lighter percentages allow more reps for hypertrophy and muscular endurance.
Using your numbers
For strength, work mostly in the 80–95% range for low reps. For muscle growth, the 65–80% range with moderate reps tends to be the sweet spot. Re-test or recalculate every few weeks as you get stronger so your loads keep pace with your progress.
A note on accuracy
Predicted maxes are estimates, not exact measurements. Your true 1RM depends on technique, fatigue, exercise selection, and how close to failure your set was. Use the estimate as a starting point and adjust based on how the weights actually feel in training.