Body Fat Calculator
Estimate your body fat percentage from a few tape measurements using the US Navy method.
Estimate your body fat percentage
The Body Fat Calculator estimates your body fat percentage using the well-known US Navy circumference method, which needs only a tape measure. Enter a few measurements and get an instant estimate plus a fitness category. It runs entirely in your browser, so your measurements stay private.
Why body fat matters more than weight
The scale and BMI cannot tell muscle from fat, but body fat percentage can. Two people of the same weight and height can look and feel completely different depending on how much of that weight is muscle versus fat. Tracking body fat gives a far better picture of fitness and body composition than weight alone, which is why athletes and coaches rely on it.
The US Navy method
This method estimates body fat from body circumferences and height. For men it uses neck and waist; for women it adds the hip measurement. It is not as precise as a DEXA scan or hydrostatic weighing, but it is free, repeatable, and accurate enough to track changes over time — which is what most people actually need.
How to measure correctly
- Neck — just below the larynx, sloping slightly downward at the front.
- Waist — at the navel for men; at the narrowest point for women.
- Hip (women) — at the widest point.
- Keep the tape snug but not compressing the skin, and measure relaxed.
Body fat categories
| Category | Men | Women |
|---|---|---|
| Athletic | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| High | 25%+ | 32%+ |
How to use it
- Select your sex (women also enter hip).
- Enter height, neck, waist (and hip) in centimeters.
- Read your estimated body fat percentage and category.
Private and free
All calculations run in your browser, so your measurements are never uploaded. The tool is completely free with no sign-up.
Frequently asked questions
How accurate is the US Navy method?
It is a reasonable estimate — typically within a few percent of more advanced methods — and excellent for tracking changes over time.
What measurements do I need?
Height, neck, and waist for men; women also measure the hip. All in centimeters.
Why is body fat better than BMI?
Body fat distinguishes muscle from fat, while BMI only uses height and weight and can misclassify muscular people.
Is my data private?
Yes. Everything is calculated in your browser and nothing is uploaded or stored.