The body fat works like this: it estimates body fat percentage from waist, neck and height measurements using the US Navy circumference method. Everything happens on your device - the input never leaves your tab unless the tool clearly states it performs a server-side lookup.
How to use the Body Fat Calculator
Enter the values the calculator asks for.
Double-check the unit or period next to each field (per month vs per year, cm vs m).
Read the result together with the breakdown shown beneath it.
Adjust one input at a time to compare scenarios side by side.
Features
Estimate body fat percentage using measurements
Instant result, no page reload
Works in any modern browser, desktop or mobile
Free with no signup
Common mistakes to avoid
Mixing units or periods between fields
Rounding inputs before the final calculation
Treating estimates as guarantees for major decisions
Examples
Input
Result
Male · waist 90cm · neck 38cm · height 175cm
Estimated body fat ~18.3%
Best used for
Getting a reliable answer for body fat without installing an app
One-off tasks done in under a minute from any device
Checking results before committing them to something important
Working on a phone where desktop software is unavailable
Privacy
Calculations run in your browser. Enter only what the calculation needs.
Frequently asked questions
How accurate is the Navy method?
Usually within 3-4% of DEXA scans when measurements are taken correctly - consistent technique matters more than absolute accuracy for tracking trends.
How do I measure waist and neck correctly?
Measure at the narrowest point of the waist and just below the larynx for the neck, tape level and snug but not compressing skin - the Navy method is sensitive to a centimetre of sloppiness.
Does the Navy method work for women?
Yes, with the women's equation which adds hip circumference - the tool switches formulas by the sex you select and shows which one produced the number.