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U.S. Navy Body Fat Calculator

Estimate body fat percentage using U.S. Navy anthropometric waist, neck, and hip measurements.

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Health & Wellness DisclosureThis calculator provides general informational estimates based on standard mathematical formulas and public health guidelines. It is not medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before making changes to your diet, exercise routine, or medical care.

Mathematical Formula

Navy Male %BF = 495 / (1.0324 - 0.19077*log10(waist - neck) + 0.15456*log10(height)) - 450

Overview & Explanation

The U.S. Navy Body Fat formula provides a practical method to estimate body fat percentage using tape measurements.

How It Works

Measures waist, neck, and hip circumferences.
Evaluates logarithmic body density.
Converts density to body fat percentage.

Practical Applications

Fitness composition tracking.
Military readiness evaluation.

How the U.S. Navy method works

The Navy method estimates body-fat percentage from tape measurements, so you do not need calipers or a scanner. Men measure the neck and the waist at the navel; women also measure the hips at the widest point. The equations use the logarithm of the difference between girths and height, because fat stored around the waist and hips increases those measurements faster than lean tissue does.

For men (in centimetres): body fat % = 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450. Women use waist + hip − neck and different constants. The formula was validated against underwater weighing and usually lands within about 3 to 4 percentage points of it.

Worked example

A man 178 cm tall with an 86 cm waist and 38 cm neck: waist − neck = 48, log10(48) = 1.681 and log10(178) = 2.250. The denominator is 1.0324 − 0.3207 + 0.3478 = 1.0595, so body fat ≈ 495 / 1.0595 − 450 = 17.2 percent. That is within the typical "fitness" to "average" range for adult men.

Measuring accurately

Measure in the morning, standing relaxed, with the tape level and snug but not compressing the skin. Take each measurement twice and use the average. Small errors matter: a 1 cm change in waist measurement shifts the result by about one percentage point, so compare results over time using the same technique.