One-Rep Max Calculator
Predict your one-rep max from a set taken to near-failure.
Estimating your strength ceiling
Your one-rep max is the heaviest weight you can move once with good form. Actually testing it is risky and fatigue-intensive, so strength programs usually estimate it from sets of 3–10 reps using formulas like Epley or Brzycki. These estimates are accurate within 5% for most lifters.
Programs use percentages of 1RM to target different training adaptations: 85–95% for pure strength, 70–80% for hypertrophy, 60–70% for power. Getting your estimate right is critical — too-heavy programming causes injury, too-light programming causes stagnation.
Frequently asked questions
Why estimate 1RM instead of testing?
True 1RM tests are high-risk (injury) and fatigue-intensive (recovery takes days). Rep-max formulas (Epley, Brzycki) estimate 1RM from a lighter set to failure, typically accurate within 5%. Used to program percentage-based lifts without the wear of testing.
What's a 'good' 1RM?
Novice strength standards (1× bodyweight targets): bench press, back squat 1.5×, deadlift 2×, overhead press 0.75×. Intermediate: bench 1.25×, squat 2×, deadlift 2.5×. Advanced: bench 1.5×, squat 2.5×, deadlift 3×. Women's standards are typically 70–80% of men's at the same training age.
Epley vs. Brzycki — which formula is better?
Both are accurate up to ~10 reps. Epley tends to overestimate at higher rep ranges; Brzycki underestimates. This calculator shows multiple formulas so you can compare. For programming, the average or the most conservative estimate is safest.
How often should I re-test my 1RM?
Real testing: every 3–6 months, at most. Estimation via a heavy triple or five: monthly. Too-frequent maxing causes nervous-system fatigue and plateaus. Programming off of 85–90% of estimated 1RM is typical.
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