Body Fat Calculator
Estimates body fat percentage using the U.S. Navy circumference method — neck, waist (and hip for women) measurements plus height — and classifies the result by sex. A practical estimate that needs no special equipment, though it's less precise than methods like DEXA scans or professional skinfold calipers.
All calculations happen on your device.
The tape-measure (US Navy) method is a common circumference-based estimate — not a substitute for a precise DEXA scan or hydrostatic weighing. For general informational purposes only.
What this tool does
Estimates body fat percentage from tape measurements of body circumference using the US Navy method, and shows which category the figure falls into.
When to use it
- Tracking how your body composition changes with a training or nutrition plan.
- Wanting an indicator closer to reality than body mass index alone.
- Having no specialist measuring equipment and wanting a tape-based estimate.
How to use it
- Choose your sex.
- Enter your height, neck circumference and waist circumference, plus hip circumference for women.
- Run the calculation and read the percentage and category.
A practical example
Input
Circumference measurements for an adult, in centimetres.
Output
An estimated body fat percentage with the category it falls into.
Limitations
- The tape method is a common circumference-based estimate and is not a substitute for a precise measurement by DEXA or hydrostatic weighing. For general information only.
- Accuracy depends entirely on your measuring: a single centimetre difference at the waist shifts the result noticeably, so measure at the same point in the same way every time.
- The equation is built on particular population samples and can be less accurate outside them.
- Tracking the trend over time is more useful than fixating on one number, because a consistent measuring error cancels out when comparing.
Privacy and processing
All calculations happen on your device and your measurements are never sent to a server.
Technical notes
- The equation works on the logarithm of body circumferences together with height, which is why it requires a hip measurement for women but not for men.
Frequently Asked Questions
This is a widely used practical formula, not a substitute for a precise medical measurement like a DEXA scan. Accuracy varies slightly with individual fat distribution, so treat the result as an approximate marker for tracking change over time rather than an absolute number.