One Rep Max (1RM) Calculator
Estimate your one-rep max based on weight lifted and reps completed. Essential for programming strength training and tracking progress.
Most accurate with 1-10 reps
Enter your lift details to calculate your one rep max.
How It Works
This calculator uses the Epley formula: 1RM = Weight × (1 + Reps/30). It's most accurate when using sets of 10 reps or fewer. Higher rep sets become less reliable for estimating max strength.
Frequently Asked Questions
Why not just test my actual 1RM?
Testing true 1RM is taxing on your nervous system and carries injury risk, especially for beginners. Estimating from submaximal sets lets you program effectively while reducing risk. Save actual 1RM tests for competition or occasional benchmarks.
How do I use this for programming?
Use percentages of your 1RM to determine working weights. For strength (1-5 reps), work at 85-95%. For hypertrophy (6-12 reps), use 67-85%. For endurance (12+ reps), stay below 67%. Progress by increasing weight when you hit the top of your rep range.
How often should I recalculate?
Recalculate every 4-8 weeks or whenever you hit a significant rep PR. Beginners may see faster progress and need more frequent updates. Your 1RM for different exercises may progress at different rates.