1RM (One-Rep Max) Calculator
Estimate your one-rep max from any weight and rep count. See training percentages for strength, hypertrophy, and volume.
Formulas are estimates. They're most accurate between 2-8 reps. Beyond 10 reps, estimates become unreliable. The "average" option blends all three for a balanced estimate.
Training percentages
How to use this calculator
Enter the weight you lifted and the number of reps you performed to failure (or within 1-2 reps of failure). The calculator estimates your 1RM using three industry-standard formulas — Epley, Brzycki, and Lander — and returns training percentages you can use in a program.
Why 1RM is a useful reference
Serious strength programs prescribe working weights as a percentage of your 1RM. This normalizes training across differently-strong lifters and keeps progression systematic. If your 1RM squat is 300 lb, a program might ask for 5 sets of 3 at 85% = 255 lb. That's how programs like 5/3/1, Juggernaut, and Smolov function.
Estimating without true testing
Testing actual 1RMs is stressful, time-consuming, and risky — a failed rep under a loaded bar can injure you. For 99% of lifters, estimating from a 3-8 rep max is plenty accurate. Just make sure the set is genuinely near failure; if you stopped because the clock hit 8 reps but you had 2 more in the tank, the estimate will be low.
Training intensity zones
50-60%: Technique, warm-up, speed work. 65-75%: Volume and hypertrophy (8-12 reps). 75-85%: Strength-hypertrophy hybrid (5-8 reps). 85-92%: Max strength (2-5 reps). 92-100%: Peak/testing (1-2 reps, sparingly). Most weekly programming lives in the 65-85% zone.
Progressing without re-testing
Every few weeks, run a rep-max set at a working weight (e.g., try to hit 6+ reps at 75%). When you clearly beat your prior estimate, re-plug the new numbers into the calculator. Your 1RM has gone up; the prescribed weights across your program adjust automatically.
Frequently asked questions
Which 1RM formula is most accurate?▾
None is perfect — each was derived from small samples and assumes you pushed the set to true failure. Epley tends to slightly overestimate; Brzycki is more conservative; Lander is close to average. Using the average of all three usually lands within 2-5% of actual strength for intermediate lifters. Near-failure matters more than formula choice.
How many reps give the most accurate estimate?▾
Between 2 and 8 reps. Fewer reps (1-2) are measuring something very close to your max anyway. More than 8-10 introduces fatigue and pacing effects that throw off the math. For an accurate estimate, pick a weight you can lift 3-6 times maximally.
Why shouldn't I test my actual 1RM often?▾
True 1RM testing is high-risk (injury potential), CNS-taxing (requires days to recover), and the numbers don't tell you much day-to-day. Powerlifters and Olympic lifters test maxes in meets; everyone else should use submaximal estimates and track progressive overload in the 3-10 rep range.
What do the training percentages mean?▾
They're common intensity zones used in strength programs. 85-95% of 1RM builds max strength (low reps, long rest). 70-85% builds hypertrophy (moderate reps, moderate rest). 50-70% is for technique work and high-volume training. Programs like 5/3/1, GZCLP, and Texas Method use percentages of 1RM to prescribe working weights.
Does 1RM transfer across lifts?▾
Not directly. Your squat 1RM doesn't tell you your bench 1RM. You need to test (or estimate) each lift separately. Common ratios for intermediate lifters: squat ≈ 1.5× bench press, deadlift ≈ 1.2× squat, overhead press ≈ 0.65× bench. These are averages; individual variation is large.
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