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● Body composition

Your body fat percentage.

The US Navy formula uses simple circumference measurements — neck, waist and hips — to estimate body fat without skinfold calipers.

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Body Fat — Navy Method
US Navy circumference formula — instant body composition estimate
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Your measurements

in
in
in
in
lb
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Your results

— %
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Enter your measurements

Body fat—
Category—
Lean mass—
Fat mass—
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How it's calculated

The US Navy circumference formula

The Navy body fat calculator estimates body fat percentage using neck, waist and hip circumferences together with height in a logarithmic equation developed by Hodgdon and Beckett in 1984. For a man who is 5 ft 9 in tall (175 cm), with a 34 in (86 cm) waist and 15 in (38 cm) neck, the estimated body fat is approximately 19% — placing him in the average category.

The formula uses circumference measurements at the neck and abdomen (and hips for women). The neck approximates lean mass; the waist (and hips for women) approximate fat. Height provides the scaling factor.

Men: %BF = 495 ÷ (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450

Women: %BF = 495 ÷ (1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)) − 450
  1. 1
    Convert all inputs to centimetres (if imperial)
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  2. 2
    Apply the Navy logarithmic formula
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  3. 3
    Classify result into category (ACE references)
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  4. 4
    Calculate lean mass and fat mass from body weight
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Understand the terms

Essential fat
The minimum body fat required for normal physiological function. Below this level, health risks rise rapidly.
Lean mass
Everything in your body except fat — muscles, bones, organs and water. Higher lean mass generally indicates better physical fitness.
Circumference method
Uses tape-measure readings instead of skinfold calipers or DEXA to estimate body fat. Less precise but accessible and consistent for tracking.
See the full glossary →
Disclaimer: estimation tool for informational and planning purposes, using the Hodgdon & Beckett (1984) formula and ACE category references. Accuracy is approximately ±3–4% compared to DEXA scans. Results do not account for age, ethnicity or muscle distribution. Not a substitute for assessment by a doctor, dietitian or certified fitness professional.
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Frequently asked questions — Body Fat (Navy Method)

How accurate is the Navy body fat method?
The US Navy formula has a margin of error of about 3–4% body fat compared to DEXA scans. It is less precise than hydrostatic weighing or DEXA but far more accessible. For tracking trends over time it works very well — just be consistent with how and when you take measurements.
Why does the Navy method use neck and waist measurements?
Research by Hodgdon and Beckett (1984) found that circumference measurements at the neck and abdomen (and hips for women) predict body fat percentage with reasonable accuracy using a logarithmic formula. It avoids skinfold calipers, which require trained technique.
Where exactly do I measure my waist for the Navy formula?
For men, measure at the navel (belly button). For women, measure at the narrowest point of the abdomen. Keep the tape horizontal and parallel to the floor, and exhale normally before reading. Avoid sucking in your stomach.
What body fat percentage is considered athletic?
For men, athletic body fat is generally 6–13%. For women, 14–20%. Essential fat (the minimum required for survival) is below 5% for men and below 12% for women. The fitness category runs 14–17% for men and 21–24% for women.
Can I use the Navy method if I have a very muscular neck?
A larger neck circumference results in a lower estimated body fat percentage in the Navy formula, since neck size is used as a proxy for lean mass. Very muscular people may get a slightly underestimated body fat result. For athletes, a DEXA scan or hydrostatic weighing gives a more accurate reading.

📚 Learn more — official sources

🏛️ Organization US Navy / DoD — Body Composition Assessment Official Human Performance Resource Center guide to the Navy body fat calculation method used by the US military. See official source → 🔬 Study Hodgdon & Beckett (1984) — Original Navy formula The original research paper establishing the circumference-based body fat estimation method adopted by the US Navy. See on PubMed → 🏛️ Organization ACE — Body Fat Percentage Categories American Council on Exercise reference for body fat percentage categories by sex and fitness level. See official source → 📘 Guide NSCA — Body Composition Testing National Strength and Conditioning Association guide on methods for assessing body composition in athletes and active individuals. See official source →

About the Body Fat Navy Method Calculator

The US Navy body fat formula, developed by Hodgdon and Beckett in 1984, remains one of the most widely used field methods for estimating body composition. It requires only a soft tape measure and takes under two minutes — making it far more accessible than laboratory methods like DEXA or hydrostatic weighing.

Results are estimates for tracking and planning, provided free and with no sign-up required. For precise body composition assessment or health decisions, consult a registered dietitian, sports medicine physician or certified fitness professional.

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