What is a one rep max?

The heaviest weight you can lift once with good form.

Which formula is best?

They give similar results. Epley and Brzycki are the most commonly used.

What percentage of 1RM should I train at?

Around 85–95% for strength, and 65–80% for muscle growth. Follow a programme suited to your experience.

One Rep Max Calculator

Enter the weight you lifted and the reps you completed to estimate the most you could lift for one rep, with a training-percentage table.

Your Set

Weight lifted (kg)

Reps completed

Estimated one-rep max from any submaximal set using four classic formulas, plus a percentage table for training loads.

Formula

Epley: w × (1 + reps/30). Brzycki: w × 36 ÷ (37 − reps). Lombardi: w × reps^0.10. O'Conner: w × (1 + 0.025 × reps).

Reference Values

•Best accuracy from 3–6 rep sets
•90–95% 1RM for strength work
•70–85% for hypertrophy

FAQ

Common questions about One Rep Max Calculator

How we calculate this

We use the standard published formula for this calculation, and we show the working so you can check it.

Spotted a mistake? Tell us and we'll check it within a few days. See how we check our calculators.

Medical disclaimer

This tool gives a general estimate for information only. It is not medical advice and cannot diagnose a condition. Talk to a doctor, midwife or other qualified professional about your own situation.