Body Fat Calculator
Estimate adult body-fat percentage using a circumference-based formula commonly associated with the U.S. Navy tape-measure method. The calculator uses height, neck and waist measurements for the male equation and height, neck, waist and hip measurements for the female equation. This is an estimate, not a clinical body-composition measurement.
Measurements are converted internally to inches before applying the published circumference equations.
Male equation uses height, abdomen/waist and neck. Female equation uses height, waist, hip and neck.
How to use the Body Fat Calculator
- Choose metric or US customary units and the equation sex category.
- Enter height, body weight and neck circumference.
- Enter abdomen or waist circumference. The female equation additionally uses hip circumference.
- Metric measurements are converted internally to inches because the displayed circumference equations are calibrated using inch measurements.
- The equation uses base-10 logarithms of the relevant circumference difference and height.
- Estimated fat mass equals body weight multiplied by estimated body-fat percentage. Lean mass is the remaining body mass.
- Tape placement, breathing, hydration and measurement technique can change the estimate, so repeat measurements consistently if tracking change over time.
Examples
Male circumference example
For a male equation using 70 inches height, 34 inches abdomen and 15 inches neck, the circumference difference is 19 inches before applying the logarithmic formula.
Female circumference example
The female equation uses waist plus hip circumference minus neck circumference together with height.
Metric measurements
Centimeter inputs are converted to inches before the circumference formula is evaluated, so users can work in either measurement system.
Frequently asked questions
How does this body-fat calculator work?
It applies circumference-based equations using height and tape measurements. The male and female equations use different measurement combinations and regression coefficients.
Is the result a medical measurement?
No. It is an estimate from body circumferences. Clinical or laboratory body-composition methods can produce different results.
Why does measurement technique matter?
Small differences in tape placement or tension change the circumference values entered into the formula, which can change the estimated percentage.
Why is hip circumference required for the female equation?
Hip circumference is one of the variables included in that published circumference equation.
What is fat mass?
The calculator estimates fat mass by multiplying total body weight by the estimated body-fat percentage.
What is lean mass?
Here lean mass means total body weight minus estimated fat mass. It includes muscle, bone, organs, water and other non-fat mass.
Is this the same as a current official military assessment?
No claim is made that this calculator reproduces any current official military fitness assessment. It uses a published circumference-based body-fat equation for educational estimation.
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