Body fat calculator
The US Navy circumference method. A tape measure beats a bathroom scale for body composition.
Method: US Navy circumference. Best accuracy when measurements are taken with a flexible tape, no compression, on bare skin.
Why circumference, not the scale
Bathroom-scale bioimpedance estimates swing wildly based on hydration, meal timing, and how recently you exercised — daily variation of ±3% body fat on the same scale is normal. Circumference measurements are slower but much more stable, and the US Navy method has been validated against hydrostatic weighing (the gold standard before DEXA) within ±3% for most people.
How to measure properly
- Waist— at the level of the navel, after a normal exhale, no breath holding, no tape compression. Stand naturally; don't suck in.
- Neck— just below the larynx (Adam's apple), head looking straight ahead, tape level all the way around.
- Hip (women) — at the widest point of your hips and buttocks, feet together.
Measure first thing in the morning, after using the bathroom and before drinking water. Same conditions every time matters more than which time of day.
Healthy ranges
For men, the "fitness" band sits roughly at 14–18%, and visible six-pack abs typically appear below 12%. For women, the corresponding bands are 21–25% (fitness) and below 18% (very visible muscle definition). Going below the "essential" threshold for extended periods isn't healthy for either sex.
Pair this with
Body fat % alone tells you composition; pair it with BMI for size and TDEE for energy budgeting. Three numbers together give a fuller picture than any one alone.