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Body Fat Calculator

The US Navy tape method — a body-fat estimate you can do at home.

What this calculates

This is the circumference method the US Navy has used for decades: a tape measure, two or three measurements, and an equation. It will not match a DEXA scan to the decimal, but it is free, repeatable at home, and honest about which direction you are moving.

Common questions

How accurate is the tape method?

Typically within about 3–4 percentage points of a DEXA scan for most people, and rather worse at the extremes. Its real strength is consistency — measured the same way each time, it tracks change reliably even when the absolute number is a little off.

How should I measure?

Use a flexible tape, keep it level and snug without compressing, measure on bare skin, and do it first thing before eating. Take each measurement twice and use the average. Measuring the same way every time matters more than measuring perfectly once.

What is a healthy body fat percentage?

Broadly 14–24% for men and 21–31% for women, with athletic ranges below that and essential fat lower still. Women carry more essential fat than men for physiological reasons, which is why the bands differ.

What can I do with the number?

Two useful things. It gives you lean mass, which is a better basis for a protein target than total weight; and it feeds the Katch–McArdle equation, which is the most accurate BMR formula when you have a reliable body-fat figure.

Estimates for healthy adults — not medical advice, diagnosis or treatment. If you are pregnant or breastfeeding, under 18, managing a condition such as diabetes or thyroid disease, or have a history of disordered eating, talk to a doctor or a registered dietitian before acting on any of this.

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Content last reviewed 29 August 2026. Estimates for healthy adults, not medical advice.