What this tool does
Estimate body-fat percentage from height and body circumferences with the U.S. Navy circumference method.
How to use it
- Choose the measurement profile used by the formula.
- Measure height, neck and waist; the female profile also requires hip circumference.
- Enter all measurements in centimetres and review the estimate rather than treating it as a diagnosis.
Formula and method
Measurements are converted to inches. The male equation uses log10(waist − neck) and log10(height); the female equation uses log10(waist + hip − neck) and log10(height). The constants follow the circumference method implemented on this page.
Worked example
For the male profile, height 175 cm, neck 40 cm and waist 85 cm produce an estimate of about 15.4%. Small changes in tape placement can change the result.
Common uses
- Following a consistent measurement trend
- Comparing results taken with the same tape protocol
- Getting a quick screening estimate without special equipment
Limitations
This method estimates rather than directly measures body fat. Hydration, body shape, tape tension and measurement site affect the result. It is not suitable for diagnosis or for making treatment decisions without a qualified health professional.
FAQ
Where should I measure?
Use the measurement sites and tape technique described by the method, keep the tape level and snug, and repeat under similar conditions.
Why does a smart scale show another number?
Bioelectrical impedance and circumference equations use different assumptions, so individual readings are not directly interchangeable.