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Body Fat Calculator

Estimate your body fat percentage from a few tape-measure circumferences using the U.S. Navy method — no calipers or scales required. Enter your measurements to see your result and fitness category.

Measurements

Measure at the narrowest part of the neck and at the navel (women also at the widest hip).

Body fat
17.6%

  • Category
  • MethodU.S. Navy
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How it works

The U.S. Navy method estimates body fat from body circumferences (in inches) using a logarithmic formula. For men:

%BF = 86.010·log10(waist − neck) − 70.041·log10(height) + 36.76

For women (hip measurement is added):

%BF = 163.205·log10(waist + hip − neck) − 97.684·log10(height) − 78.387

Measure the neck at its narrowest, the waist at the navel, and (for women) the hips at the widest point.

Worked example

A man 70 in tall with a 34 in waist and 15 in neck:

Frequently asked questions

How accurate is the U.S. Navy body fat method?
It's a reasonable estimate — typically within a few percentage points of more precise methods like DEXA — and far more convenient since it needs only a tape measure. Accuracy depends on measuring at the right spots consistently. For medical decisions, use a clinical method.
What is a healthy body fat percentage?
It differs by sex. For men, roughly 14–24% is considered average-to-fit and 6–13% is athletic. For women, who naturally carry more essential fat, about 21–31% is average-to-fit and 14–20% is athletic. Very low body fat carries its own health risks.
Why do I need to measure my neck?
The neck circumference is subtracted from the waist (and hip) to approximate the fat distribution around your midsection relative to your frame. It's what lets the formula work from tape measurements alone.

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