Body Fat Calculator
Estimate body fat percentage from height, neck, waist and hip measurements using the US Navy method.
Tip: Take the measurements at the same time of day with a flat, non-stretch tape. Repeat them and use the average.
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About this digital tool
A body fat calculator estimates the share of your weight that is fat tissue. This tool uses the US Navy method, which needs only a flexible tape measure. For men it uses height, neck and waist circumference. For women it also uses hip circumference. The formula works with logarithms of these measurements and returns a percentage that is compared with common category ranges. The result is a practical estimate for tracking progress over time, not a laboratory measurement. Accuracy depends on how precisely you measure, and it can differ by a few percentage points from methods such as DEXA or hydrostatic weighing. For medical questions, speak with a clinician.
How to use
- Enter your sex, height and weight.
- Measure your neck just below the larynx and your waist at the navel, then enter both values.
- For women, also measure the widest part of the hips.
- Read the estimated body fat percentage and its category.
Frequently asked questions
What is a healthy body fat percentage?
For men, about 10–20% is a common normal range. For women, about 18–28%. Athletes often sit lower: roughly 6–13% for men and 14–20% for women.
How accurate is the US Navy method?
It usually lands within a few percentage points of more precise methods. It is useful for following your own trend over time, but it is not exact.
Where should I measure my neck, waist and hips?
Measure the neck just below the larynx, the waist at the navel after a normal breath out, and the hips at their widest point. Keep the tape level and snug but not tight.
Why does the result change with small measurement differences?
The formula uses logarithms of the measurements, so an error of 1 cm at the waist can shift the result noticeably. Measure two or three times and use the average.