Body Fat Calculator

Estimate your body fat percentage using the U.S. Navy circumference (tape measurement) method, from your height, neck, waist, and (for women) hip measurements.

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Enter your height, neck, and waist (and hip, if female) circumference to estimate your body fat percentage using the U.S. Navy method.

Sex

Male

Female

Height *

Neck circumference *

Waist circumference *

Your result

17.80%

Estimated body fat

AI explanation

Formula

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

Worked example

Male, 180cm, neck 38cm, waist 85cm

Worked example: Male, 180cm, neck 38cm, waist 85cm
Field	Value
Sex	male
Height	180
Neck circumference	38
Waist circumference	85
Hip circumference	100
Estimated body fat	16.1

Assumptions

Uses the U.S. Navy circumference method (Hodgdon & Beckett, 1984), a tape-measurement estimate rather than a direct body-composition measurement (like DEXA or hydrostatic weighing).
Measurement technique significantly affects accuracy — measure waist at the navel and neck just below the larynx, keeping the tape snug but not compressing the skin.
Informational only — not a clinical measurement.

Frequently asked questions

How accurate is the Navy body fat method?

It's generally within a few percentage points of more precise methods like DEXA scans for most people, making it a reasonably good field estimate, though accuracy depends heavily on correct measurement technique.

Why does the formula need a hip measurement for women but not men?

The Navy method uses different regression formulas for men and women, developed separately from body-composition data — the female formula factors in hip circumference because fat distribution patterns differ by sex.

Where exactly should I measure my waist and neck?

Measure your neck just below the larynx (Adam's apple), and your waist at the level of your navel. Keep the tape snug against the skin without compressing it.

Related calculators

Sources

Prediction of Percent Body Fat for U.S. Navy Men and Women from Body Circumferences and Height — Naval Health Research Center. Effective 01-08-1984, reviewed 13-09-2026.

This calculator provides a general estimate only and does not constitute personalized medical advice. For an accurate body composition assessment, consider a DEXA scan or consult a healthcare professional.

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