Body Fat Calculator — U.S. Navy Method
Estimate your body fat percentage from tape measurements using the U.S. Navy circumference method, metric or imperial.
Where to put the tape: Neck: just below the larynx (Adam’s apple). Waist: horizontally, at the navel.
The Navy method’s published error against underwater weighing is about ±3.5 percentage points, so this reading most likely sits between 14.9% and 21.9%.
| Category | Range | |
|---|---|---|
| Essential | 2–5% | |
| Athletes | 6–13% | |
| Fitness | 14–17% | |
| Average | 18–24% | You |
| Obese | 25%+ |
The U.S. Navy method is a rough estimate, not a medical measurement — talk to a healthcare professional for a real assessment.
Estimate body fat from a tape measure
The U.S. Navy circumference method (which the Navy used for its own body-fat standard until a waist-to-height screen replaced it at the end of 2025) estimates body fat percentage from a few tape measurements — height, neck and waist (plus hip for women) — with no scale or calipers needed. Enter measurements in centimetres or inches and get a percentage and a general fitness category.
An estimate, not a diagnosis
This is a screening estimate, not a medical measurement. Circumference formulas can be off by several points versus a DEXA scan, and body fat is only one signal of health. For a real assessment, talk to a healthcare professional. A reading in the Essential band adds a line on what too little fat does — hormones, bones, the body's defence against illness — and one in the Obese band names the conditions high body fat is linked with; both point you to a doctor. Your measurements are never uploaded — everything runs in your browser.
Frequently asked questions
How does the U.S. Navy body fat method work?
It uses log-based formulas on your height, neck and waist (and hip for women) circumferences to estimate body fat percentage — no scale required.
How accurate is it?
It is a rough estimate. It tracks trends reasonably but can differ from lab methods like DEXA by several percentage points. Treat it as a guide, not a diagnosis.
Do I measure in cm or inches?
Either — switch units and enter all measurements in the same system. Measure the neck just below the larynx, and the waist at the navel for men or at the narrowest part of the abdomen for women — the “Where to put the tape” line under the boxes says the same.
Can it tell me my fat mass, or how much fat to lose?
Yes, if you fill in the two optional boxes. A Weight, in kg or lb to match the Units select, adds "Fat mass" and "Lean mass". An Age adds "Ideal for your age (Jackson & Pollock)" and how far you are from it — "Fat to lose to reach ideal" when a weight is given, "Above ideal" in percentage points when not. That table covers a limited span of adult ages, and outside it the page says so rather than guessing.
Is there a second estimate to check this one against, and how far off can it be?
Yes. With a weight and an age filled in, “Body fat, BMI method” stands beside the Navy figure — Deurenberg's adult equation from your BMI, age and sex — for the range of adult ages the page names. Under the answer, a line gives the Navy method's published error against underwater weighing and turns it into the range your reading most likely sits in.
Does it warn when a reading is too low as well as too high?
Yes. A reading in the Essential band adds a line on what too little body fat does — hormones fall out of balance, bones thin and the body fights illness less well — and says to raise it with a doctor if the reading is real. One in the Obese band names what high body fat is linked with: high blood pressure, type 2 diabetes, heart disease and some cancers. The bands in between get no warning.