One Rep Max Calculator

Calculate your one rep maximum for any exercise using multiple validated formulas.

Enter Your Values

Weight Lifted (lbs)

Reps Completed

Unit

Results

Fill in your values above and click Calculate.

Frequently Asked Questions

Q.Which 1RM formula is most accurate?

The Epley formula is most commonly used. For lower reps (1-5), all formulas are more accurate. For higher reps (10+), accuracy decreases.

Q.Why calculate 1RM?

1RM helps plan training loads. Most programs use percentages of 1RM — e.g., 80% for hypertrophy, 85-95% for strength, 70% for endurance.