One Rep Max Calculator

Estimate your one-rep max (1RM) from a recent set, using the Epley and Brzycki formulas.

Weight Lifted (kg)

Reps Performed Most accurate for 1–10 reps performed near failure

Estimated One Rep Max

Training Percentages (based on your estimated 1RM):

How One Rep Max Is Estimated

This tool averages two well-known formulas:

Epley: 1RM = weight × (1 + reps ÷ 30)

Brzycki: 1RM = weight ÷ (1.0278 − 0.0278 × reps)

Both are most accurate for sets of 10 reps or fewer performed close to failure.

They are most accurate for sets of 10 reps or fewer performed close to failure; accuracy decreases with higher rep counts.

No single formula is perfect for everyone. Averaging the Epley and Brzycki estimates usually gives a reasonable middle-ground figure.

Estimated 1RM is a planning tool, not a guarantee. Work up gradually with a spotter if attempting a true max lift.

Last Updated: July 2026