Your body fat percentage, with a tape measure.
Three or four measurements, and the U.S. Navy method gives you an estimate in seconds. The math runs in your browser: nothing is sent anywhere.
Your measurements
Just below the Adam’s apple.
At the navel, after a normal breath out.
Optional: adds your fat mass and lean mass.
Result
| Category | Body fat |
|---|---|
| Essential fat | 2–5% |
| Athletes | 6–13% |
| Fitness | 14–17% |
| Average | 18–24% |
| Above average | 25%+ |
An estimate within about 3–4 points of a DEXA scan. To track change, measure under the same conditions every time.
Your measurements stay on your device.
The calculation runs in your browser: no measurement is sent to us or to anyone else, and nothing is stored. You can even go offline once the page has loaded.
How to take your measurements
A soft tape measure, on bare skin.
Flat, level, snug without squeezing. A tape that slips or digs in can shift the result by several points.
Neck: just below the Adam’s apple.
Look straight ahead, shoulders relaxed, with the tape angled slightly down toward the front.
Waist: at the navel for men, at the narrowest point for women.
Stand relaxed and measure at the end of a normal breath out — don’t suck your stomach in.
Hips: around the widest part of the glutes.
Feet together, tape level all the way around. This one only goes into the formula for women.
In the morning, under the same conditions.
Before eating and before training: that’s what makes two measurements comparable week to week. Take each one twice and keep the average.
One number says little. A trend says a lot.
Body Tracker keeps your weight and measurements next to your progress photos, date by date, and reminds you of every check-in. Free, no account, and everything stays on your phone.
Frequently asked questions
How does the U.S. Navy method work?
It estimates body density from your height and your neck, waist and (for women) hip circumferences, then converts it into a body fat percentage. The equations were published by Hodgdon and Beckett in 1984 and are still used by the U.S. military.
How accurate is it?
Expect it to land within about 3–4 points of a DEXA scan, sometimes more for very muscular or heavier builds. It’s a reference, not a clinical measurement — but measured the same way every time, it tracks a trend very well.
What body fat percentage should I aim for?
According to the American Council on Exercise, 14–24% for men and 21–31% for women covers the “fitness” and “average” categories. Below essential fat (about 2–5% for men, 10–13% for women), health is at risk. For a personal target, talk to a health professional.
Are my measurements saved?
No. The calculation runs in your browser; nothing is sent or kept. To keep a history, the Body Tracker app stores your measurements on your phone.