How accurate is a 1RM calculator?

Most accurate with 1-10 reps. Accuracy decreases above 10 reps. The Epley and Brzycki formulas are typically within 5% for trained lifters.

Why should I know my 1RM?

Knowing your 1RM lets you program training at the correct intensity. Hypertrophy training uses 60-80% 1RM, while strength training uses 80-95% 1RM.

Free Tool

One Rep Max (1RM) Calculator

Calculate your one rep max for any exercise. Enter your weight and reps to estimate your 1RM using the Epley, Brzycki, and Lombardi formulas.

Weight Lifted (lbs/kg)

Reps Completed

About This Calculator

Your one-rep max (1RM) is the maximum weight you can lift for a single repetition. Knowing your 1RM helps program training percentages for strength, hypertrophy, and power phases without actually testing a heavy single.

Formula: Epley: weight × (1 + reps/30)

Frequently Asked Questions

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