About Workout Math Calculators

Last updated June 5, 2026

I’m a recreational runner and lifter who wanted the actual pace, one-rep-max, and training math without a fitness-influencer wrapper. Results here are estimates with the formulas shown — not coaching or medical advice.

What’s on this site

Right now there are 6 calculators here: Running Pace Calculator, One Rep Max Calculator, Calories Burned Calculator, Race Time Predictor, Navy Body Fat Calculator, and Protein Intake Calculator. Each one is a single-purpose tool that shows its formula, lists its assumptions, and runs on any device with no signup.

Why these are different

A lot of calculators are black boxes — you get a number and no way to tell if it’s right. These work the other way around: the formula, the constants, and a worked example sit on the page next to the result, so you can redo the math by hand. No account, no paywall, no signup.

How the math is kept honest

Each formula is shown in full and was independently re-derived and spot-checked against the calculator’s code. Reference values (typical rates, averages, rules of thumb) are labeled as approximate and are editable, so you can put in your own real numbers. Nothing here is medical, dietary, or training advice — talk to a qualified professional about your own body and health.

Found a mistake?

I’d genuinely like to know. Email [email protected] and I’ll fix it.