Calculate your 1 Repetition Maximum (1RM) for any exercise.

1RM Calculator

The 1RM (One Repetition Maximum) is the maximum weight with which a single repetition of a particular exercise can be done.

Since testing your actual 1RM is very risky and expensive for the central nervous system, you can estimate it using various mathematical formulas based on the weight you can lift for multiple repetitions.

Available Formulas

This calculator supports multiple 1RM estimation formulas, each with different characteristics and accuracy for various rep ranges:

  • Brzycki

    Most accurate for reps ≤ 10. Formula: weight / (1.0278 - 0.0278 × reps)

    weight / (1.0278 - 0.0278 × reps)
  • Epley

    Popular and widely used. Formula: weight × (1 + reps / 30)

    weight × (1 + reps / 30)
  • Lombardi

    Good for powerlifting. Formula: weight × reps^0.10

    weight × reps^0.10
  • Mayhew et al.

    Accurate for higher rep ranges. Formula: weight × (100 / (52.2 + 41.9 × e^(-0.055 × reps)))

    weight × (100 / (52.2 + 41.9 × e^(-0.055 × reps)))
  • O'Conner et al.

    Good for general strength training. Formula: weight × (1 + reps / 40)

    weight × (1 + reps / 40)
  • Wathan

    Accurate across various rep ranges. Formula: weight × (100 / (48.8 + 53.8 × e^(-0.075 × reps)))

    weight × (100 / (48.8 + 53.8 × e^(-0.075 × reps)))

Choosing a Formula

Different formulas work better for different scenarios:

  • Brzycki: Most accurate for rep ranges ≤ 10. Recommended for most users.
  • Epley: Popular and widely used, good general-purpose formula.
  • Lombardi: Good for powerlifting and explosive movements.
  • Mayhew et al.: Accurate for higher rep ranges.
  • O'Conner et al.: Good for general strength training.
  • Wathan: Accurate across various rep ranges.

You can select your preferred formula from the dropdown menu in the calculator. The default formula is Brzycki, which works well for most training scenarios.

Important Notes

  • These formulas provide estimates, not exact values. Actual 1RM may vary based on individual factors.
  • Formulas are most accurate when the number of repetitions is between 1-10.
  • Always prioritize safety when attempting maximum lifts. Consider using a spotter and proper form.
  • Different formulas may give slightly different results. Choose the one that best fits your training style.