🏋️ One-Rep Max Calculator
Enter the weight you lifted and how many reps you completed to estimate your one-rep max (1RM) and common training percentages.
What Is a One-Rep Max?
Your one-rep max (1RM) is the heaviest weight you could lift for a single complete repetition of an exercise. Because testing a true 1RM directly can be risky, most lifters estimate it from a lighter set taken close to failure.
The Epley Formula
This calculator uses the widely-used Epley formula: 1RM = weight × (1 + reps ÷ 30). It works well for rep ranges roughly between 1 and 10, and becomes less accurate at very high rep counts, so the calculator caps its estimate at 12 reps.
Using Training Percentages
The 90%, 80%, and 70% figures are common reference loads used to plan strength, hypertrophy, and endurance-focused training blocks. This tool is for general fitness planning only and is not a substitute for individualized coaching or medical advice, especially if you are new to lifting or returning from injury.