Free online tool
Body Fat Percentage Calculator
Enter a few tape measurements and get a body fat estimate using the U.S. Navy method.
How the Navy method works
The U.S. Navy developed this formula so that recruits could be assessed with nothing more than a measuring tape. It uses the ratio of waist and neck circumference (plus hip for women) against height to estimate body fat percentage. It's not as accurate as a DEXA scan, but it's remarkably close for most people and can be repeated at home for free.
Getting accurate measurements
Measure at the widest part of your waist (usually around the navel), the narrowest point of your neck (just below the Adam's apple), and — for women — the widest part of the hips. Take each measurement two or three times and average them. Keep the tape snug but not compressing the skin.
+How does this compare to a scale that measures body fat?
Home bioelectrical scales are heavily affected by hydration and often less accurate than a careful Navy-method measurement.
+What's a healthy range?
Broadly, 10–20% for men and 18–28% for women is considered healthy, but athletes and older adults sit outside those ranges.
Why use the Body Fat Percentage Calculator on ToolNest?
The Body Fat Percentage Calculator is one of more than forty free browser-based utilities we maintain on ToolNest. Every tool on the site is engineered around the same three promises: it must be fast, it must protect your privacy, and it must be genuinely useful without hiding features behind an account, a paywall, or an email capture form. Whether you use the Body Fat Percentage Calculatoronce a month or several times a day, it should feel like a native part of your workflow — open the tab, get the result, move on.
Everything happens directly inside your web browser. When you type, paste, or upload something into the Body Fat Percentage Calculator, that data never leaves your device. There is no server round-trip, no logging, no analytics pixel watching your keystrokes, and no third-party API silently receiving a copy of your input. Closing the browser tab is the same as clearing your session. This is a deliberate design choice: too many free "online tools" quietly funnel user content through remote servers, and we do not think a utility as small as this one justifies that risk.
Speed is the other pillar. The Body Fat Percentage Calculator loads on a cold connection in well under a second and stays responsive on older phones, low-power laptops, and metered mobile networks. There are no heavy frameworks layered on top of the tool, no autoplay video ads, and no blocking third-party scripts. Search engines like Google reward pages that load quickly and stay interactive, but more importantly, so do human visitors who came here to get one specific job done.
If the Body Fat Percentage Calculator saves you time, the best thing you can do is bookmark this page and share it with a colleague or classmate who might need it. We also welcome direct feedback — bug reports, feature requests, and suggestions for entirely new tools all go to the same inbox and are read by a human. The best tools on ToolNest started life as a one-line reader email, and this page will keep improving as long as people keep telling us what they wish it did better.