Which 1RM formula is most accurate?
Brzycki and Epley are the most widely cited and validated in sports science literature for sets under 10 repetitions.
1RM Calculator
Calculates your estimated 1RM from submaximal repetitions using seven peer-reviewed strength equations, alongside a comprehensive 1 to 12 rep percentage loading chart.
Scientific Formula & Exercise Physiology Standards
Equation: Brzycki, Epley, Lander & Lombardi Equations | Peer-Reviewed Source: National Strength and Conditioning Association (NSCA)
Brzycki: W ÷ (1.0278 - 0.0278×R) | Epley: W × (1 + 0.0333×R)
Where W is weight lifted and R is repetitions completed. Computes exact estimates across 7 standard scientific equations and provides the multi-formula average.
Step-by-Step Worked Example: 1RM Estimation (100 kg for 5 reps)
- Epley formula: 100 × (1 + 0.0333 × 5) = 116.65 kg
- Brzycki formula: 100 ÷ (1.0278 - 0.0278 × 5) = 112.51 kg
- Lander formula: (100 × 100) ÷ (101.3 - 2.67123 × 5) = 113.71 kg
- 7-Formula Average = 114.3 kg
Calculation Result: Estimated 1RM = 114.3 kg (252.0 lbs)
Clinical Nuances, Limitations & Best Practices
- Accuracy is highest between 1 and 8 repetitions. Formulas become less reliable above 10-12 reps.
Frequently Asked Questions (1RM Calculator)
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