The body fat calculator estimates percentage body fat using the U.S. Navy circumference method. It uses height and tape measurements to offer an accessible approximation without specialized body-composition equipment.
How to use this calculator
Select the appropriate published formula and enter height, neck, and waist in centimeters. The female formula also requires hip circumference. Measure with a level, snug tape without compressing the skin and use consistent anatomical positions.
Formula & calculation method
The Navy equations use logarithms of height and circumference differences, with separate coefficients for male and female formulasThe male equation uses waist minus neck together with height; the female equation uses waist plus hip minus neck. Logarithms use centimeter values in this implementation, and the result is an estimated percentage rather than a direct fat measurement.
Worked example
Small tape-placement changes can alter the result. Repeating measurements under similar conditions and using the average of consistent readings can improve the reliability of your input even though the estimate remains approximate.
Why this is useful
The method requires only simple measurements and gives a repeatable way to monitor trends. Displaying the formula's assumptions helps users understand why consistent technique matters more than minor decimal changes.
Limitations to keep in mind
Circumference equations can be inaccurate for unusual body shapes, high muscle mass, pregnancy, and some populations. Hydration and measurement technique also matter. Clinical body-composition assessment requires appropriate professional methods.
Frequently asked questions
Where should I measure my waist?
Use a consistent waist site according to a reliable measurement guide. Do not switch between the narrowest point and navel level when tracking changes.
Why does the female formula need hip measurement?
The published female Navy equation includes hip circumference, while the male equation does not.
Is this more accurate than BMI?
It uses different information but is not necessarily more accurate for every person. Both are screening estimates with limitations.