1RM Calculator (One Rep Max Strength)
Calculate your one-rep max (1RM) and percentage training loads for bench press, squat, and deadlift.
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How to Use the 1RM Calculator
- 1Select your exercise (Bench Press, Squat, Deadlift, Overhead Press).
- 2Enter the weight lifted (in lbs or kg).
- 3Enter the number of repetitions completed with good form (1 to 12 reps recommended).
- 4Review your estimated 1RM across standard formulas alongside percentage training zones (50%–95%).
Formula & How It Works
Brzycki & Epley 1RM Formulas
Matt Brzycki's formula is renowned for accuracy under 10 reps, while Boyd Epley's equation is widely favored in collegiate athletics.
Worked Examples
Bench Press 225 lbs for 5 Reps
Input: 225 lbs × 5 reps
Explanation: Brzycki formula calculates 225 × (36 / 32) = 253.1 lbs.
Squat 315 lbs for 3 Reps
Input: 315 lbs × 3 reps
Explanation: Low-rep sets (3–5 reps) provide the most accurate predictive correlation for true 1RM strength.
Frequently Asked Questions
Why should I use a 1RM calculator instead of testing max weight?▼
Testing a true 1RM to physical failure carries significant injury risk to tendons and joints. A calculator safely estimates maximum strength using moderate working sets.
Up to how many reps is the 1RM calculator accurate?▼
Formulas are most reliable between 2 and 10 repetitions. Sets above 12 reps test muscular endurance rather than maximal strength.
What is a 5x5 training percentage of 1RM?▼
A standard 5x5 working program typically uses approximately 75% to 80% of your 1RM.
Is this medical advice?▼
Not medical advice. Always use a spotter and warm up adequately before attempting heavy resistance training.
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