One Rep Max Calculator

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Strength training tool

Estimate your one rep max from a completed set and use the result to plan sensible training loads.

Estimated 1RM using Epley116.7 kg

257.3 lbs

Formula comparison

Epley116.7 kg
Brzycki115.3 kg

Training percentages

Suggested loads based on your estimated Epley 1RM.

IntensityKgLbs

What is a one rep max?

Your one rep max, or 1RM, is the heaviest weight you can lift for one complete repetition with controlled technique. An estimated 1RM helps you plan training without repeatedly testing a true maximum.

How do you calculate 1RM?

This calculator uses the Epley formula: weight multiplied by (1 + reps / 30). It also shows the Brzycki formula, weight multiplied by (36 / (37 - reps)), so you can compare two common estimates.

Epley vs Brzycki

Both formulas estimate maximal strength from a submaximal set, but they can produce slightly different results. Treat the numbers as useful training guidance rather than an exact measurement.

Tips for using your estimate

  • Use a recent set completed with consistent form.
  • Start conservatively when choosing a new training weight.
  • Warm up properly and stop if technique breaks down.
  • Recalculate after a meaningful change in strength.