One Rep Max Calculator
Estimate the maximum weight you can lift for one repetition.
Best accuracy under 10 reps
What is a One Rep Max?
Your One Rep Maximum (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise. It is the gold standard for measuring pure strength.
Formulas Used
This calculator averages results from the most accurate formulas:
- Brzycki Formula: Weight × (36 / (37 - Reps))
- Epley Formula: Weight × (1 + (Reps / 30))
- Lombardi Formula: Weight × Reps^0.10
Safety First
Testing a true 1RM is physically demanding and risky without a spotter. Using a calculator to estimate it from a 3-5 rep set is much safer.