Body Fat Percentage Calculator is a free tool that estimates body fat with the U.S. Navy tape-measure method: height, waist and neck for men, plus hips for women. It also works out your waist-hip ratio against WHO risk bands. A tape measure is the only equipment, and nothing you enter leaves your browser.
How to measure body fat with tape
- Pick Metric or Imperial and your Sex (the formulas differ).
- Measure Height standing straight, Waist at the navel relaxed, and Neck just below the Adam’s apple.
- Women add Hips at the widest point; men can still add it for the waist-hip ratio.
- Read Body fat with its band, and the Waist-hip ratio risk beside it.
What 17.5% actually means
A man of 178 cm with an 86 cm waist and 38 cm neck scores about 17.5% — the top of the Fit band, edging toward Average. The same tape on a 163 cm woman (71 cm waist, 97 cm hips, 33 cm neck) reads about 26.6%, mid-Average for women, whose healthy range sits higher because essential fat does too. Compare either against the blunt instrument of weight-over-height in the BMI Calculator: the two disagree most for muscular builds, which is exactly when body fat tells the truer story.
Why the second number matters as much
Total fat and risky fat are different problems: belly fat predicts heart disease better than the headline percentage. A waist-hip ratio under 0.90 for men or 0.80 for women is low risk by WHO bands regardless of the body-fat reading. And once you know the composition, the next question is fuel — price it with theTDEE Calculator.
Frequently asked questions
How accurate is the Navy method?
Within about 3–4 percentage points of DEXA scans for most people — good for tracking change, rough for bragging rights. It assumes average fat distribution, so very muscular or very lean bodies read less well.
Where exactly do I measure?
Height standing straight; neck just below the Adam’s apple; waist at the navel, relaxed, tape horizontal; hips at the widest point (women). Measure twice and use the average — a centimetre of slack moves the result.
What does waist-hip ratio add?
Where fat sits matters independently of how much there is: belly fat predicts cardiovascular risk better than total fat. Under 0.90 (men) or 0.80 (women) is low risk by WHO bands, whatever the body-fat number says.
Is this medical advice?
No. It applies published formulas to tape measurements you take yourself. Body composition screening is a starting point — training, diet and health decisions deserve a professional.
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