How Body Fat & Ideal Weight Calculator works
Your body fat percentage offers more nuance than BMI alone. This calculator uses the US Navy circumference method, requiring only a tape measure, to estimate body fat from height, neck and waist (plus hip for women).
It also shows your Devine ideal weight (1974), a reference value widely used in clinical dosing, so you see both composition and a reference target at a glance. All measurements are in centimetres, and the method lands within about 3 to 4 percentage points of a DEXA scan, a practical estimate rather than a clinical measurement.