Body Fat Calculator

Estimate your body fat percentage from a few tape-measure readings using the U.S. Navy method: height, neck and waist (plus hips for women). See your category, and add your weight to get fat mass and lean mass — metric or imperial.

This tool runs entirely in your browser.

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How to use the Body Fat Calculator

1Choose metric or imperial units and your sex.
2Measure your height, neck (just below the larynx) and waist — at the navel for men, the narrowest point for women — and hips for women.
3Optionally enter your weight, then read your body fat percentage and category.

What is the Body Fat Calculator?

The U.S. Navy method estimates body density from circumferences using the Hodgdon–Beckett equations; it was developed to assess personnel without lab equipment. It is typically within about 3–4 percentage points of methods like DEXA, and less accurate for very muscular or very lean people.

Categories follow the American Council on Exercise (ACE): for men, 14–17 % is “fitness” and 25 % or more “obese”; for women the ranges are about 7–8 points higher. This is an estimate, not medical advice.

Frequently asked questions

How should I measure?

Use a flexible tape, keep it level and snug without compressing the skin, measure relaxed (not sucking in), and take the average of two or three readings.

Is body fat better than BMI?

It tells you more about composition: two people with the same BMI can have very different body fat. Both are screening tools, not diagnoses.

Is the Body Fat Calculator free and private?

Yes. The Body Fat Calculator is free, needs no account, and runs entirely in your browser. What you type is never sent to a server or stored.

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