Always free, no sign-up

Fitness calculators that actually explain the number

Free tools for strength training, nutrition, and body composition — real formulas, real explanations, no guesswork.

Browse by category

Every tool is grouped by what it helps you do.

Free, no sign-up, and every one comes with a plain-English explanation of the maths.

Estimate your single-rep max from any working set, with a full percentage table.

Type the weight you want and see which plates go on each side, with the bar drawn out.

Find your real maintenance calories from what you ate and what your weight did.

A daily protein range for your weight and goal, with a per-meal split and the research behind it.

A daily fiber target from your calories, or from your sex and age, with the research behind it.

The US Navy method: three tape measurements, no calipers or scans.

Turn reps and effort into a percentage of your max and a working weight.