1RM Calculator
Estimate your one-rep max from any weight and rep combination. Uses three proven formulas for accurate results.
Calculate Your 1RM
About 1RM Formulas
Epley Formula: Most accurate for lower rep ranges (1-6 reps). Commonly used in strength training.
Brzycki Formula: More conservative estimates. Better for higher rep ranges (6-12 reps).
Lander Formula: Middle ground between Epley and Brzycki. Good all-around accuracy.
Note: These are estimates. Your actual 1RM may vary based on factors like fatigue, technique, and training experience. Always use a spotter when testing maxes.
Frequently Asked Questions
What is a 1RM (one rep max)?
A 1RM is the maximum weight you can lift for a single repetition with proper form. It's used to measure strength progress and calculate training loads as percentages.
How accurate are 1RM calculators?
1RM calculators are most accurate for rep ranges of 1-10. Accuracy decreases with higher reps (10+). They provide estimates; your actual 1RM may vary based on fatigue, technique, and experience.
Which 1RM formula is best?
For low reps (1-6), the Epley formula is most accurate. For higher reps (6-12), Brzycki tends to be more conservative and realistic. We show all three formulas so you can compare.
How often should I test my 1RM?
Testing true 1RMs is taxing on your body. Most lifters test every 8-12 weeks. Using calculators between tests is safer and gives you training guidance without the recovery cost.
What percentage of 1RM should I train at?
For strength: 80-90% (3-6 reps). For hypertrophy: 65-80% (6-12 reps). For endurance: 50-65% (12+ reps). Most programs periodize across these ranges.
Track Your Strength Automatically
This calculator gives you a snapshot. Arvo tracks your estimated 1RM for every exercise, shows progression over time, and automatically adjusts your training loads based on performance.
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