One Rep Max Calculator
Estimate your 1RM (one repetition maximum) for any lift using weight and reps performed. Calculate training percentages for programming.
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How to use this calculator
w = weight lifted; r = number of reps completed with that weight. Most accurate for 2–10 reps.
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Enter the weight you lifted and how many reps you completed with that weight.
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The Epley formula estimates your one-rep maximum.
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Use the percentage table for programming: 75–85% for hypertrophy sets, 85–95% for strength.
Frequently asked questions
How accurate is the 1RM estimate?
The Epley formula is most accurate for 2–10 reps. Accuracy decreases for high-rep sets (>15) because factors like muscular endurance play a larger role. For best results, test with a weight you can lift 3–8 times.
What percentage of 1RM should I train at?
55–65% for muscular endurance (15+ reps); 67–85% for hypertrophy (8–15 reps); 85–95% for strength (1–5 reps); 95–100% for maximal strength/power work.
Should I actually attempt a true 1RM?
Only with proper technique, warm-up, and a spotter. For most training purposes, estimating 1RM from a submaximal lift is safer and sufficient for programming.
1RM Calculator — One Rep Max & Training Percentages
Why 1RM matters for strength programming
Percentage-based training anchors every working set to your maximum strength. Without knowing your 1RM, you can't precisely control training intensity. Most powerlifting, Olympic lifting, and strength-focused programs (5/3/1, Westside, Texas Method) are built around 1RM percentages.
Epley vs other 1RM formulas
Several formulas exist: Epley (1 + r/30), Brzycki (36 / (37 − r)), and Lander (1 / (1.013 − 0.0267123 × r)). They produce similar results for moderate reps. Our calculator uses Epley because it tends to perform well across a wide rep range and is most widely used in sports science literature.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →