1RM Calculator
Calculate your one-rep max (1RM) for any lift based on the weight and reps you can perform. Uses the Epley and Brzycki formulas.
What is a One Rep Max (1RM)?
Your one rep max (1RM) is the maximum weight you can lift for a single repetition with proper form. It's the gold standard for measuring absolute strength and is used to program training percentages.
Rather than actually attempting a true 1RM (which carries injury risk), you can estimate it by lifting a lighter weight for multiple reps and using a formula.
How to Use Your 1RM
- Strength (1-5 reps): 85-100% of 1RM — heavy loads, long rest periods.
- Hypertrophy (6-12 reps): 65-85% of 1RM — moderate loads, the classic muscle-building range.
- Endurance (12+ reps): 50-65% of 1RM — lighter loads, shorter rest.
Formulas Used
Epley Formula: 1RM = Weight x (1 + Reps/30). Simple and widely used. Most accurate for 1-10 reps.
Brzycki Formula: 1RM = Weight x 36/(37 - Reps). Slightly more conservative. Also most accurate for low rep ranges.
Both formulas become less accurate above 10 reps. For the most reliable estimate, use a weight you can lift for 3-5 reps.
Related Calculators
TDEE Calculator
Calculate your Total Daily Energy Expenditure (TDEE) to understand how many calories you burn each d...
BMR Calculator
Calculate your Basal Metabolic Rate (BMR) to find out how many calories your body burns at rest usin...
Macro Calculator
Calculate your optimal daily intake of protein, carbs, and fat based on your goals - whether you wan...
Calorie Deficit Calculator
Calculate the right calorie deficit for safe and sustainable weight loss. Find out exactly how many ...