One Rep Max Calculator

Estimate your maximum lifting strength from a weight you can lift for several reps. See your estimated one rep max and recommended working weights across training percentages.

Enter the weight you lifted and the number of repetitions you completed (1–15 reps for best accuracy). The calculator uses the Epley equation to estimate your one rep max, then shows recommended working weights for warm-up, hypertrophy, strength and power.

Estimated 1 rep max
50% — warm-up
65% — recovery / speed
70% — hypertrophy
80% — strength
90% — power / peaking

A one rep max (1RM) calculator predicts the heaviest weight you can lift once from a lighter weight lifted for several reps — the safest way to gauge strength without maxing out, and the basis for percentage-based training.

The maths

The Epley equation:

1RM = weight × (1 + reps / 30)

It is most accurate for 1–10 reps. Beyond ~15 reps the estimate gets less reliable. Working weights are simply a percentage of the 1RM.

Examples

  • 80 kg × 8 reps ≈ 101 kg 1RM
  • 100 kg × 5 reps ≈ 117 kg 1RM
  • Train hypertrophy around 70% (≈7 reps), strength at 80–85% (≈5 reps)

Frequently asked questions

Which formula is best?

Epley is a solid all-rounder. Brzycki and Lombardi agree closely in the 1–6 rep range. Whatever you pick, use it consistently to track progress.

Should I actually test my 1RM?

Only with good form and a spotter. For most goals, sub-maximal testing (a heavy set of 3–5) fed into this calculator is safer and nearly as informative.

Just for the giggles, much love.
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