1RM Calculator

Estimate your one-rep max using popular formulas like Epley, Brzycki, Lombardi, Mayhew, and O'Conner.

What Is a 1RM Calculator?

Calculate your estimated one-rep max from any weight and rep count.

Uses four validated formulas (Epley, Brzycki, Lombardi, Mayhew) and provides a training percentage chart.

How to Calculate Your 1RM

Follow these steps:

  • Choose your preferred unit system.
  • Enter the weight you lifted.
  • Enter the number of reps you completed.
  • Click calculate to see your estimated 1RM.

Tips

  • Use 3-5 reps for the most accurate 1RM estimate.
  • Ensure proper form when testing.
  • Use training percentages to set workout weights.

Frequently Asked Questions

What is a 1RM?+
Your one-rep max (1RM) is the maximum weight you can lift with proper form. It is used to set training percentages and track strength progress.
Which 1RM formula is most accurate?+
Brzycki and Epley are the most commonly used and tend to be accurate for 1-10 reps. All formulas become less accurate above 10 reps. For best accuracy, test with a weight you can lift 3-5 times.
How do I train using my 1RM?+
Common training zones: Strength: 80-90%, 3-5 reps. Hypertrophy: 65-80%, 8-12 reps. Endurance: 50-65%, 15-20 reps. Power: 50-70%, 3-6 explosive reps.

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1RM Calculator — free online 1rm calculator, one rep max calculator, strength calculator, weightlifting calculator, training percentages. No signup required. Works in your browser.