Body Fat Calculator: The Navy Tape-Measure Method
No scan, no scales, no clinic visit — just a tape measure and a formula. Here is how the Navy method turns circumferences into a body fat estimate.
What is the Body Fat Calculator?
The US Navy method estimates body fat from circumferences — waist and neck for men, plus hip for women — combined with height in a logarithmic formula. It is a cheap, equipment-free estimate, not a scan, so expect a few percentage points of error. The result is general information only, not medical advice, and trends over time matter more than any single reading.
How to use it
- Enter your height, waist, and neck measurements in centimetres.
- Women: also enter your hip measurement.
- Read your estimated body fat percentage.
Worked example
A man 175 cm tall with a 90 cm waist and 40 cm neck has an estimated body fat of 19.21% by the Navy formula.
Can a tape measure really estimate body fat?
Reasonably well, yes. The Navy formula was built by comparing tape measurements against lab body-composition tests across many people, and it captures the pattern that a larger waist relative to neck and height usually means more body fat. It is not as precise as a DEXA scan, but repeated the same way it tracks change over time quite usefully.
Frequently asked questions
How do I measure correctly?
Measure waist at the navel, neck below the Adam's apple, and hip at the widest point, with the tape snug but not tight, and do not hold your breath.
How accurate is the Navy method?
It is usually within a few percentage points of lab methods for average builds, but less reliable for very muscular or very lean people.