What this calculator measures
Your one-repetition maximum (1RM) is the heaviest load you can lift for a single clean repetition with full range of motion. Knowing your estimated 1RM lets you set percentage-based training loads (e.g., 70–80% for hypertrophy, 85–95% for strength), track progress over months, and compare training blocks meaningfully.
How this calculator works
We use the Epley formula — weight × (1 + reps ÷ 30) — one of the most widely validated 1RM prediction equations for multi-joint exercises. Accuracy is highest for submaximal sets of 6 reps or fewer and decreases slightly as rep count rises above 10. The calculator also shows common training percentages to guide programming.
How to use your result
Use a recent near-maximal set — ideally 3–6 reps at a challenging weight where form stays tight. Avoid estimating from sets completed to failure, as technique breakdown inflates the estimate. Retest every 4–8 weeks as a benchmark for strength progress, and use the training percentages to structure your weekly programming.
Important limitation
Calculator results are estimates. Pregnancy, eating disorders, medical conditions, injuries, or concerning symptoms require qualified professional guidance.