Body Fat Calculator

The Body Fat Calculator estimates body-fat percentage from sex, height, neck circumference, waist circumference, and hip circumference for women. It uses the US Navy circumference method and assigns a broad category.

Calculation method

Measurements entered in imperial units are converted to centimetres. The calculator then estimates body density and converts density to body-fat percentage with the Siri relationship:

For men: $\text{Density}=1.0324-0.19077\log_{10}(\text{Waist}-\text{Neck})+0.15456\log_{10}(\text{Height})$

For women: $\text{Density}=1.29579-0.35004\log_{10}(\text{Waist}+\text{Hip}-\text{Neck})+0.22100\log_{10}(\text{Height})$ $\text{Body fat}=\frac{495}{\text{Density}}-450$

The displayed percentage is rounded to one decimal place and categorized using sex-specific ranges in the module.

Measurement guidance

Take circumference measurements consistently and avoid comparing results taken under different conditions. The calculator requires a hip measurement for women and requires the waist measurement to exceed the neck measurement in the modeled equations.

Questions

Is this result exact?

No. Circumference placement, tape tension, hydration, body shape, and the equation's population assumptions create measurement error.

Does it measure visceral fat?

No. It estimates total body-fat percentage from external measurements and cannot identify fat distribution or health risk on its own.

Is a category a medical diagnosis?

No. The category is a broad informational band. Discuss body-composition or health concerns with a qualified clinician.

Health notice and limitations

This calculator is educational and does not replace clinical assessment. It does not use DEXA, bioimpedance, skinfold calipers, blood tests, age, athletic training, pregnancy status, or medical history.