Body Fat Calculator
Estimate body fat percentage using height and tape measurements of your waist, neck and, for one equation, hips. Switch between centimetres and inches and see your result instantly.
Enter your measurements
Use a flexible measuring tape and enter values carefully. The selected equation determines which circumferences are needed.
Enter your measurements and calculate to see the percentage and method used.
Estimated body fat
The ring is a visual representation of the number, not a medical risk category.
How to measure correctly
Keep the tape horizontal, snug but not compressing skin. Follow a consistent anatomical location for the chosen method.
Measure at the specified neck location with the tape level. Small differences affect the estimate.
For the female equation, measure around the widest part of the buttocks.
For comparisons over time, use the same tape, posture, measurement points and technique.
How the body fat calculation works
This calculator uses the circumference-based U.S. Navy-style equations from the supplied ToolZippy page. The male equation combines height with waist minus neck circumference. The female equation combines height with waist plus hip minus neck circumference.
These equations use base-10 logarithms. The calculation standardizes entered measurements to centimetres before applying the centimetre-form coefficients. Changing the display unit to inches does not change the underlying estimate.
Is this a direct measurement?
No. Circumference equations estimate body fat percentage using body dimensions. They cannot directly measure fat mass, muscle mass or body composition, and results can differ from laboratory or clinical methods.
How to use this calculator
- Choose the equation appropriate for the reference method.
- Select centimetres or inches.
- Enter height, waist and neck measurements.
- Enter hip circumference if the female equation is selected.
- Select Calculate Body Fat and review the estimate.
The result is intended for adults as a general educational estimate. It should not be used alone to make health or weight-management decisions.
Understanding the limitations
The formula is sensitive to tape placement, body shape and individual differences. Repeated measurements are more useful when collected consistently, but even a consistent estimate can differ from actual body fat percentage.
Health information: This tool is not a diagnosis or medical recommendation. It is not intended for pregnancy-related decisions, eating-disorder management, or other high-stakes health choices. Consult a qualified professional when precise assessment matters.
Body Fat Calculator FAQs
Is the calculator free?
Yes. It requires no signup.
Why is a hip measurement sometimes required?
The female circumference equation includes hip measurement; the male equation does not.
Can I enter measurements in inches?
Yes. The tool converts inch measurements to centimetres internally before calculation.
Is the result exact?
No. It is an estimate based on circumference measurements, not a direct body composition test.
Does the tool measure body fat distribution?
No. It estimates an overall percentage and does not assess where fat is stored.