Body Fat Percentage Calculator (US Navy)

About this calculator

This calculator estimates body fat percentage using the U.S. Navy circumference method, which combines height with neck and waist measurements (plus hip for women) in a logarithmic formula instead of relying on weight or BMI. Because it uses body measurements rather than scale weight, it distinguishes between fat mass and lean mass in a way a bathroom scale cannot — two people with the same weight can have very different body fat percentages.

The U.S. military has used this method for decades to assess recruits' fitness for service, and it remains popular because it needs only a tape measure rather than calipers, a DEXA scan or a hydrostatic tank. Gym-goers and people tracking body recomposition use it to see whether they're losing fat or losing muscle, and the result is typically mapped to a health category (essential fat, athletic, fitness, average or obese) for context.