One Rep Max Calculator
Calculate your estimated one-rep maximum based on weight and reps performed
(1-12 reps recommended for accuracy)
What is One Rep Max?
One Rep Max (1RM) is the maximum amount of weight you can lift for a single repetition with proper form. It's a key metric in strength training used to measure progress, plan training programs, and determine appropriate working weights. Knowing your 1RM allows you to train at specific percentages for different goals - strength, hypertrophy, or endurance.
1RM Formulas Explained
Several formulas estimate your 1RM from submaximal lifts. The Epley formula (1RM = weight × (1 + reps/30)) works best for 6-10 reps. The Brzycki formula (1RM = weight × 36/(37-reps)) is more accurate for lower rep ranges (1-6). The Lander formula provides a good middle ground. All formulas become less accurate above 10-12 reps. For best results, use a weight you can lift for 3-6 reps with good form.
How to Use Your 1RM
Once you know your 1RM, you can plan training loads effectively. For maximum strength (1-5 reps), work at 85-100% of 1RM. For strength and size (6-8 reps), use 75-85%. For hypertrophy (8-12 reps), use 65-75%. For muscular endurance (12-15+ reps), use 50-65%. Remember that these are estimates - always prioritize proper form and use a spotter for heavy lifts.