About the Body Fat Percentage Calculator
Body fat percentage is often a more useful health metric than weight or BMI alone, since it distinguishes between fat mass and lean mass (muscle, bone, organs, water). Two people can weigh the same and have the same BMI while having very different body compositions and health risk profiles.
This tool uses the U.S. Navy circumference method, developed by the U.S. Navy in the 1980s as a fast, equipment-free field alternative to skinfold calipers or hydrostatic weighing. It uses simple tape-measure inputs — neck, waist, and (for women) hip circumference — and cross-references them against height using a logarithmic formula validated in military fitness testing.
Frequently Asked Questions
How accurate is the Navy method compared to a DEXA scan?
It typically has a margin of error of around 3-4%, which is accurate enough for tracking trends over time but not a substitute for clinical body composition testing like DEXA or hydrostatic weighing.
Where exactly should I measure my waist?
Measure at the navel, keeping the tape level and snug but not compressing the skin. Measure at the end of a normal exhale for consistency.
Why do men and women use different formulas?
Fat distribution patterns differ by sex — women typically carry more essential fat and store it differently — so the Navy method uses separate equations, adding a hip measurement for women.