Body Fat Calculator (US Navy)
Circumference method · neck, waist, (hip for women), height
The U.S. Navy method estimates body-fat percentage from tape measurements instead of calipers. For men: %BF = 86.010·log₁₀(waist − neck) − 70.041·log₁₀(height) + 36.76. For women, add the hip measurement: %BF = 163.205·log₁₀(waist + hip − neck) − 97.684·log₁₀(height) − 78.387. Measurements are in inches in the original formula; enter cm or inches below and it converts for you. Add your weight to also see fat and lean mass.
Source: Hodgdon & Beckett, 1984 (U.S. Navy).
Estimate only; general fitness information, not medical advice or a diagnosis.
The formula (inches)
Men: %BF = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76
Women: %BF = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387
Fat mass = weight × %BF / 100
Lean mass = weight − fat massReference ranges
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletic | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| High | 25%+ | 32%+ |
General reference ranges (American Council on Exercise style categories).
Pair this with the ideal body weight calculator and the TDEE calculator to plan a cut or recomposition. For how accurate tape methods really are, read the US Navy body-fat method explained.
Frequently asked questions
How does the US Navy body-fat method work?
It estimates body-fat percentage from tape measurements of the neck, waist (and hips for women) plus height. For men: %BF = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76, in inches. Women add the hip measurement. Lean mass is then your weight minus the estimated fat mass.
How accurate is the US Navy body-fat formula?
It is generally within about 3–4 percentage points of a DEXA or hydrostatic measurement for most people, which is good for a tape measure. It can be off for very lean or very muscular individuals because it does not measure fat directly — it infers it from circumferences.
Where exactly should I measure?
Neck: just below the larynx, tape sloping slightly down to the front. Waist: at the navel for men, at the narrowest point for women. Hip (women): at the widest point of the buttocks. Measure relaxed, breathe normally, and keep the tape snug but not compressing the skin.
What is a healthy body-fat percentage?
Rough reference ranges: men, 6–13% athletic, 14–17% fit, 18–24% average, 25%+ high. Women carry more essential fat: 14–20% athletic, 21–24% fit, 25–31% average, 32%+ high. These are general guides, not diagnostic thresholds.