Online Tool Store
Body Fat Percentage Calculator
Estimate adult body fat percentage with the circumference method and review approximate fat and lean mass using metric or imperial measurements.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Estimated body fat
17.1%
Estimated fat mass
13.3 kg
Estimated lean mass
64.7 kg
Circumference estimates are sensitive to tape placement and cannot measure body composition directly.
How to estimate body fat percentage
- Select the applicable measurement equation and unit system.
- Enter height, neck, waist, optional hip where shown, and body weight.
- Review the estimated percentage plus approximate fat and lean mass.
Circumference equations
Measurements are converted to inches. The male equation uses waist − neck; the female equation uses waist + hip − neck. Logarithmic circumference and height terms produce the estimated percentage. Weight then divides total mass into estimated fat and lean portions.
Do not use this estimate as medical advice or an official military/occupational assessment. A qualified professional can help interpret body-composition measurements.
FAQ
Which measurements are required?
Both equations use height, neck, and waist circumference. The female equation also uses hip circumference. Weight is used only to estimate fat and lean mass.
Where should circumference measurements be taken?
Measurement protocols differ. Use a flexible tape, keep it level and snug without compressing skin, and follow one consistent published protocol when comparing results.
Is a tape estimate the same as a body composition scan?
No. Circumference equations estimate body fat statistically and can differ from DEXA, air-displacement, underwater weighing, or other assessments.
Why can a small tape difference change the result?
The equations use differences between circumferences inside logarithms, so tape placement, breathing, tension, and rounding can affect the estimate.
Can this result diagnose a health condition?
No. It is a general adult estimate and does not diagnose health, fitness, nutritional status, or suitability for any programme.
How we compare
| Feature | Online Tool Store | Calculator.net | Professional body composition test |
|---|---|---|---|
| Circumference estimate | Included | Navy and BMI methods | Method dependent |
| Metric and imperial inputs | Included | Included | Provider dependent |
| Direct composition measurement | No | No | Possible with specialist methods |
Choose Calculator.net when you want several estimation methods side by side, or a qualified provider for an appropriate body-composition assessment. Online Tool Store offers a transparent circumference estimate with fat and lean mass context.