Strength Training
One Rep Max Calculator
Estimate your one-rep max from a set you can already do, and get useful training percentages for programming.
How to Read Your Result
Your one-rep max (1RM) is the most weight you can lift for a single repetition. This calculator estimates it from a lighter set using the Epley and Brzycki formulas. Estimates are most accurate at lower rep counts (about 1-10 reps).
Estimates are most reliable when reps are between 1 and 10.
Use percentages of 1RM to program: hypertrophy often 65-80%, strength 85%+.
Never test a true 1RM without a warm-up, good form, and a spotter.
Frequently Asked Questions
What is a one-rep max?
Your one-rep max (1RM) is the maximum weight you can lift for one full repetition of an exercise.
How accurate are 1RM formulas?
They are good estimates at low rep counts. Accuracy drops as reps rise above about 10-12.
How do I use 1RM percentages?
Programs prescribe loads as a percentage of 1RM - for example 70% for hypertrophy or 85%+ for strength.