One Rep Max Calculator

One-Rep Max FAQ

What is a one-rep max (1RM)?

Your one-rep max is the maximum weight you can lift for a single repetition with proper form. It is used to program training intensities — for example, working at 70-85% of your 1RM for hypertrophy or 85-95% for strength.

Is it safe to test my actual 1RM?

Testing a true 1RM carries higher injury risk, especially for beginners. Using an estimated 1RM calculated from a sub-maximal set (e.g., 5 reps at a given weight) is safer and nearly as accurate. Save true 1RM testing for competition prep or after several months of consistent training.

Which 1RM formula is most accurate?

No single formula is universally best. The Epley and Brzycki formulas are most widely used and tend to be accurate for sets of 1-10 reps. Accuracy decreases with higher rep counts (15+). Our calculator uses multiple formulas and shows the average for the most reliable estimate.

How often should I recalculate my 1RM?

Recalculate every 4-6 weeks or whenever you notice your working weights have changed significantly. Strength improves with training, and your percentages should update accordingly to continue progressing.