One Rep Max (1RM) Calculator

Frequently asked questions

Which formulas are used?

The Epley and Brzycki formulas, averaged. Both estimate your single-rep max from a weight you lifted for several reps.

How accurate is the estimate?

It is reliable up to about 5 or 6 reps and becomes increasingly optimistic above that. Above 12 reps it is not trustworthy.

What is the percentage table for?

It converts your estimated max into working weights for common training percentages, with an estimated rep count for each.

Is a calculated max safe to attempt?

Treat it as a guide. Build up gradually and always use a spotter or safety pins for true max attempts.