Cited formulas, no sign-up
Precise fitness calculators, built like a good tool.
TDEE, macros, one-rep max, BMI and body fat. Each one uses a published equation from sources like the NHS, WHO and ACSM, and shows its working. Free and instant.
All calculators
Five tools, each with the math, the sources and a short FAQ.
Cited formulas, no sign-up
TDEE Calculator
Daily calories you burn, from BMR and activity.
OpenMacro Calculator
Protein, carbs and fat grams for your calorie target.
OpenOne-Rep Max Calculator
Estimate your 1RM from a set, with a % loading table.
OpenBMI Calculator
Body Mass Index with WHO category thresholds.
OpenBody Fat Calculator
U.S. Navy circumference method, no calipers.
Open