Introducing the One Rep Max Calculator — Know Your Strength, Safely

Programming strength work around percentages of your one-rep max is the standard approach — but actually maxing out is risky and tiring. The new One Rep Max Calculator estimates your 1RM from a normal working set, no true max required.

What it does

• Six formulas averaged — Epley, Brzycki, Lander, Lombardi, O’Conner, Wathan.
• Min–max range so you can see how much the formulas agree.
• Training-percentage table from 50% to 100%, with typical reps at each load.
• kg or lb, with sensible rounding.

Why it matters

An estimated 1RM lets you set accurate working weights safely. To understand how the formulas work, why averaging beats any single one, and how to train with percentages, read our one-rep max guide — then fuel your lifting with the Macro Calculator.

Free, and private

The One Rep Max Calculator is free and runs entirely in your browser — nothing you enter is uploaded or stored. A future Pro upgrade is planned for logging lifts, tracking your 1RM trend, and building programs, but the estimator stays free.