DocomintBody Fat Calculator
Estimate body fat percentage from tape-measure circumferences using the US Navy method.
The US Navy circumference method estimates body fat from a tape measure rather than a scale or scan — a more direct read on body composition than BMI, since it's based on where fat actually tends to accumulate rather than a weight-to-height ratio that can't tell fat from muscle.
Example: A man at 175cm with a 38cm neck and 85cm waist comes out to roughly 15.9% body fat — comfortably within the "fitness" range most standard body-fat charts define for men (14–17%).
How it works
- Enter your gender, height, neck, waist, and (for women) hip circumference
- Press Calculate
- Your estimated body fat percentage appears instantly, computed on your device
Frequently asked questions
How accurate is the US Navy body fat method?
It's a reasonable field estimate — typically within a few percentage points of more precise methods like DEXA scanning for most body types — but less accurate for very lean or very high body-fat individuals. It's popular because it only needs a tape measure, not specialized equipment.
Why do women need a hip measurement and men don't?
The US Navy formula's constants were derived separately for each gender based on typical fat distribution patterns — women's formula factors in hip circumference because fat distribution differs from men's, where waist and neck alone were found to be sufficient predictors.
Is my numbers uploaded anywhere?
No — Body Fat Calculator runs entirely in your browser using JavaScript/WebAssembly. Your numbers is never sent to a server.