🏆 Fitness Tool
One Rep Max (1RM) Calculator
Calculate your estimated one-repetition maximum for any exercise. Plan your training loads based on your 1RM percentage.
1RM Calculator
Estimated 1 Rep Max
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Brzycki
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Epley
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Lander
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One Rep Max Formulas
The One Rep Max (1RM) is the maximum weight you can lift for one complete repetition with proper form. It is the gold standard for measuring strength and used to calculate training loads for different rep ranges and goals.
Brzycki: 1RM = Weight × (36 / (37 − Reps))
Epley: 1RM = Weight × (1 + 0.0333 × Reps)
Lander: 1RM = (100 × Weight) / (101.3 − 2.67123 × Reps)
Epley: 1RM = Weight × (1 + 0.0333 × Reps)
Lander: 1RM = (100 × Weight) / (101.3 − 2.67123 × Reps)
Training Load Percentages
- 90–100% 1RM (1–3 reps): Maximal strength
- 75–85% 1RM (6–8 reps): Strength-hypertrophy
- 65–75% 1RM (8–12 reps): Hypertrophy (muscle building)
- 50–65% 1RM (12–20 reps): Muscular endurance
Frequently Asked Questions
Is it safe to test my 1RM?
Directly testing your 1RM carries injury risk, especially for beginners. Use this calculator to estimate your 1RM from a submaximal effort (e.g., 5–10 reps) instead. Always warm up properly and have a spotter for heavy lifts.
Which 1RM formula is most accurate?
The Brzycki formula is generally considered the most accurate for lower rep ranges (1–10 reps). The Epley formula works well across all rep ranges. Accuracy decreases for reps above 10, as factors like muscular endurance become more significant.
How often should I test my 1RM?
Most intermediate and advanced lifters test 1RM every 4–12 weeks when following strength training programs. Beginners should focus on learning technique and building a base before attempting near-maximal loads.