Body Composition Formula

Body Fat Percentage Formula (US Navy)

The US Navy method estimates body fat from neck, waist, and (for women) hip circumferences. It's a regression equation, not a direct measurement, so expect ±3% accuracy versus DXA.

5 VARIABLESPublished Mar 12, 2026Updated May 10, 2026Live Content

By Orbyd Editorial · AI Fit Hub Team

Best Next MoveBody Composition

Body Fat Percentage Calculator

Estimate body fat percentage using the U.S. Navy circumference method.

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Formula 5 variables Worked example Variations

Education · Not medical advice. Output is deterministic math from your inputs.Editorial standards Sponsor disclosure Corrections

Formula

Copy the exact expression or work through it step by step below.

 Male:   BF% = 86.010·log10(waist − neck) − 70.041·log10(height) + 36.76
Female: BF% = 163.205·log10(waist + hip − neck) − 97.684·log10(height) − 78.387
(all measurements in centimeters)

Variables

BF%

Body fat percentage

Fat mass as a percentage of total body mass. Reference ranges: men 10–22% (essential fat 2–5%), women 18–32% (essential 10–13%).

neck

Neck circumference

Measure below the larynx, perpendicular to the long axis of the neck. Centimeters.

waist

Waist circumference

Men: at the navel. Women: at the narrowest point above the navel. Measure on an exhale, no compression.

hip

Hip circumference (women only)

At the widest point of the buttocks.

height

Standing height

Centimeters, barefoot.

Step By Step

1

Take all measurements with a flexible non-stretch tape, on a relaxed exhale. Repeat each three times and average.

Neck: 38.5, 38.0, 38.2 → 38.2 cm.
2

Compute the circumference difference: waist minus neck (men) or waist plus hip minus neck (women).

Male: waist 84 − neck 38 = 46 cm.
3

Apply the log10 terms. log10(46) ≈ 1.663; log10(178) ≈ 2.250.

Male: 86.010·1.663 − 70.041·2.250 + 36.76.
4

Sum the terms.

143.04 − 157.59 + 36.76 = 22.2% body fat.

Worked Example

Male, 178 cm, neck 38 cm, waist 84 cm

Sex

Male

Height (cm)

178

Neck (cm)

Waist (cm)

BF% = 86.010·log10(84 − 38) − 70.041·log10(178) + 36.76 = 86.010·1.663 − 70.041·2.250 + 36.76 = 143.04 − 157.59 + 36.76

Body fat ~22.2%. Mid-range for an average male; lean for a trained one.

Common Variations

DXA (dual-energy X-ray absorptiometry) is the most accurate non-invasive method, ±1% vs. cadaver dissection.

Skinfold caliper methods (Jackson-Pollock 3-site or 7-site) cost less but require trained technique; ±3–4% accuracy.

Bioelectrical impedance (handheld or scale) is heavily affected by hydration — useful for trend tracking only.

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Sources & References

Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height — Naval Health Research Center, Report 84-11
Body Composition Methods: Comparisons and Interpretation — Journal of Diabetes Science and Technology