Body Fat Calculator

The U.S. Navy formula estimates body fat from circumferences — neck and waist for men, plus hips for women — against height. Measured carefully (tape level, no sucking in), it lands within ±3–4% of lab methods for most people, which is comparable to consumer bioimpedance scales.

The American Council on Exercise brackets: essential fat 2–5% (men) / 10–13% (women); athletes 6–13% / 14–20%; fitness 14–17% / 21–24%; average 18–24% / 25–31%. Trends matter more than any single reading — measure at the same time of day, weekly.