Body Fat Percentage Calculator

Using the U.S. Navy tape-measure method, this estimates your body fat percentage from a few circumference measurements, and adds fat and lean mass when you include your weight. It's a general informational estimate rather than medical advice, and stores none of your inputs.

100% free
Private & safe
Runs in your browser

This tool runs entirely in your browser and needs JavaScript enabled to work. The full guide, examples and FAQ below are available without it.

Sex

Height

Neck

Waist

Weight (optional, for fat/lean mass)

Check your measurements

Enter height, neck and waist measurements.

This is a general informational estimate, not medical advice or a diagnosis. The Navy method is an approximation; measurement technique affects accuracy. Consult a qualified professional for assessment.

How to measure & category ranges

Measuring (relaxed, snug tape, not compressing skin): Neck — below the larynx. Waist — at the navel for men; at the narrowest point for women. Hip (women) — at the widest point. Height — without shoes.

Estimated with the U.S. Navy circumference formula. Typical American Council on Exercise categories:

Men — essential 2–5%, athletes 6–13%, fitness 14–17%, average 18–24%, obese 25%+. Women — essential 10–13%, athletes 14–20%, fitness 21–24%, average 25–31%, obese 32%+.

Methodology last verified August 2026.

Why use Body Fat Calculator?

Body Fat Calculator gives a quick, private estimate using well-established formulas — informational only, and nothing you enter is stored.

Runs instantly in your browser — nothing to install, nothing uploaded.
Completely free, with no account, no watermarks and no usage limits.
Handles U.S. Navy circumference method (log-based formula); Male uses waist & neck; female adds hip.
Choose metric or US units and your sex.
Works on any device — desktop, tablet and phone — and is fully keyboard accessible.

How to use Body Fat Calculator

Choose metric or US units and your sex.
Enter your height, neck and waist (and hip for women).
Optionally add your weight for fat and lean mass.
See your estimated body fat percentage and category.

Examples

Estimating body fat from waist and neck measurements.
Tracking body composition changes over time.

Supported formats & limits

U.S. Navy circumference method (log-based formula)
Male uses waist & neck; female adds hip

Limitations

An approximation; measurement technique strongly affects accuracy.
Less reliable at very high or very low body fat.
Not medical advice — consult a professional for assessment.

Frequently asked questions

How accurate is the Navy method?

It is a reasonable estimate for most people but depends on careful, consistent measuring; it is not a clinical measurement.

Is this medical advice?

No — it is a general informational estimate only.

Are my measurements stored?

No — everything is calculated in your browser and nothing is saved.

Was this tool helpful?

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