One Rep Max (1RM) Calculator
Estimate your one-rep max using 7 scientifically validated formulas. Enter a weight and rep count to see your predicted max.
Frequently Asked Questions
Which 1RM formula is most accurate?
The Epley and Brzycki formulas are the most widely used and tend to be accurate for 1-10 reps. For higher rep ranges (10-30), the Wathan and Mayhew formulas may be more reliable. We show the average of all 7 formulas for the best estimate.
How many reps should I use?
For the most accurate estimate, use a weight you can lift for 3-5 reps. The accuracy decreases as the rep count increases beyond 10. Never test with a weight you cannot safely control.
How do I use the percentage chart?
The percentage chart shows training weights based on your estimated 1RM. For example, if your 1RM is 100kg, working at 80% means using 80kg. Common training zones: 90-100% for strength, 70-85% for hypertrophy, 50-70% for endurance.