Body Fat Calculator
Estimate your body fat percentage with nothing but a tape measure — the US Navy circumference method, the same formula used for military fitness standards, with ACE category ranges.
Body fat (Navy method)
17.9%
Category (ACE)
Average
Measure the neck just below the larynx, the waist at the navel (men) or narrowest point (women), and hips at the widest point — tape level, snug but not compressing. The Navy method typically lands within 3–4% of a DEXA scan; consistency of measurement matters more than absolute precision. Educational use only.
How the Navy Method Works
The method exploits where humans store fat: the waist-to-neck difference tracks abdominal fat closely enough that a log-based regression against height predicts total body fat within a few percent of lab methods for most people. It was developed by the Naval Health Research Center so fitness tests could run with a tape measure instead of a dunk tank.
Formula (measurements in inches)
Men: 495 / (1.0324 − 0.19077·log₁₀(waist − neck)
+ 0.15456·log₁₀(height)) − 450
Women: 495 / (1.29579 − 0.35004·log₁₀(waist + hip − neck)
+ 0.22100·log₁₀(height)) − 450
ACE ranges: Men Women
Athletes 6–13% 14–20%
Fitness 14–17% 21–24%
Average 18–24% 25–31%Frequently Asked Questions
How accurate is the Navy tape-measure method?
Within about 3–4% of a DEXA scan for most people, which is comparable to consumer bioimpedance scales and far cheaper. It's least accurate for very muscular or very lean builds. The practical move: measure monthly under identical conditions and trust the trend more than any single reading.
What body fat percentage is considered healthy?
Broadly, 10–22% for men and 20–32% for women spans the fitness-to-average range in the ACE categories; athletes run lower. 'Healthy' is wider than aesthetic targets — health risks concentrate at the extremes, especially visceral fat at the high end and hormonal disruption below essential-fat levels.
Why is essential body fat so much higher for women?
Sex-specific fat in breasts, hips, and thighs plus hormone production push women's physiological minimum to about 10–13%, versus 2–5% for men. Dropping below essential levels disrupts hormones in both sexes — it's a floor for body function, not a target.
What body fat percentage do you need to see abs?
Typically under ~14% for men and ~20% for women, with sharp definition closer to 10% and 17%. Where you store fat is genetic, so two people at the same percentage can look quite different — and the last few percent come from a calorie deficit, not more ab exercises.