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One Rep Max

Your one-rep max (1RM) — the maximum weight you can lift for one repetition — is the foundation of strength programming. Most training programs prescribe loads as a percentage of 1RM. Our calculator estimates your 1RM from a submaximal lift (safer than maxing out) using five validated formulas, and generates a full percentage table for program design.

Estimated 1RM

Epley:
Brzycki:
Lombardi:
O'Conner:
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About the One Rep Max (1RM) Calculator

Your one-rep max (1RM) — the maximum weight you can lift for one repetition — is the foundation of strength programming. Most training programs prescribe loads as a percentage of 1RM. Our calculator estimates your 1RM from a submaximal lift (safer than maxing out) using five validated formulas, and generates a full percentage table for program design.

How to use it

  1. Enter the weight you lifted and the number of reps (use 2–10 reps for best accuracy).
  2. See estimated 1RM from Epley, Brzycki, Lander, Lombardi, and O'Conner formulas.
  3. View the full percentage table: 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95% of 1RM.
  4. Use the rep range calculator: find how many reps at a given weight equal what % of 1RM.

Formula & methodology

Epley (most common): 1RM = weight × (1 + reps/30). Brzycki: 1RM = weight × 36/(37 − reps). Lander: 1RM = weight × 100/(101.3 − 2.67123 × reps). Lombardi: 1RM = weight × reps^0.10. O'Conner: 1RM = weight × (1 + 0.025 × reps). Best accuracy with 4–6 rep sets.

Common use cases

  • Powerlifting programming: setting training loads for squat, bench, deadlift
  • Hypertrophy programs: 70–85% 1RM for 6–12 rep ranges
  • Strength testing: tracking progress without risky true 1RM attempts
  • Percentage-based programs (5/3/1, Westside, Texas Method)
  • Comparing strength relative to body weight (Wilks coefficient)

Frequently asked questions

At 1–5 reps, estimates are within ±2–5% of true 1RM for most people. At 8–10 reps, error increases to ±5–10% because rep-max relationships vary significantly between individuals (some people are "high rep" lifters). For best accuracy: use 3–5 rep sets for the calculation and test the actual 1RM occasionally in a controlled setting to calibrate your personal formula.
For competitive powerlifters: test peaks before meets, typically every 12–16 weeks at end of a training cycle. For general strength training: estimate via the calculator every 4–6 weeks from working sets without maxing out. True 1RM attempts are taxing on the CNS and carry injury risk — submaximal estimation is safer and accurate enough for programming purposes.

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