What we do

One Rep Max Calculators is an independent website. We make tools that answer the questions lifters ask between sets: what is my max, what should I lift today, which plates go on the bar, and how does my total compare. Every tool works in pounds and kilograms and on any phone.

We also write plain-English guides that explain the numbers: what a one rep max is, how the formulas work, how accurate they are, and how to use them in training.

How we build and check our tools

• Every formula comes from a published source, listed on how our calculators work.
• All calculators share one engine, so the same set gives the same answer on every page.
• Every release is checked by automated tests against hand-worked and published examples.
• Every claim in our guides links to a source we have read. If we can’t check a number, we leave it out.

Read our editorial policy for how we research, review and update content.

How the site is funded

The calculators are free. We plan to pay for the site with display advertising. If we ever add affiliate links (for example to lifting equipment), they will be clearly labelled, and they will never change what our calculators or guides say.

Get in touch

Spotted a mistake or have an idea for a tool? Visit our contact page.