Body Fat Calculator
Body fat percentage (US Navy method)
This free Body Fat Calculator estimates your body fat percentage with the US Navy method, a tape-measure technique developed for service personnel that needs no special equipment. For men it uses height, neck and waist measurements; for women it adds the hips. From those circumferences it estimates body density, converts that into a fat percentage, places you in a standard category from essential fat through to obese, and splits your weight into fat mass and lean mass — the muscle, bone, water and everything else.
Measure carefully for a fair result: the waist goes at navel level for men and at the narrowest point for women, the neck just below the Adam's apple, and the tape should be snug without squeezing. Even measured well, this is an estimate only, not medical advice. The Navy method is usually within a few percentage points of laboratory methods for most people, but it can misread very muscular builds and unusual fat distribution. If the number matters for a health decision, confirm it with a professional method such as a DEXA scan or clinician assessment. Your measurements are processed locally in your browser and are never uploaded or stored.
How to use
- Select your sex and the units you measured in.
- Enter your weight and standing height.
- Measure and enter your neck and waist circumferences.
- If female, also measure and enter your hip circumference.
- Click Calculate body fat to see your percentage, category and mass split.
Frequently asked questions
How accurate is the US Navy method?
For most adults it lands within roughly three to four percentage points of reference methods like hydrostatic weighing. That is good enough for tracking trends over time, which is its best use: re-measure the same way every few weeks and watch the direction, not a single reading.
Where exactly should I measure my waist?
For men, at the level of the navel with the stomach relaxed. For women, at the narrowest point of the natural waist. Measure after breathing out normally, keep the tape level all the way round, and do not pull it tight enough to dent the skin.
Why does body fat percentage matter more than weight?
Two people of the same weight can look and be very different: one may carry more muscle, the other more fat. Weight alone cannot tell them apart, and BMI cannot either. Body fat percentage separates fat from lean tissue, which is the part linked most closely to health.
What is a healthy body fat range?
Commonly used ranges put fitness-level men around fourteen to seventeen percent and women around twenty one to twenty four percent, with average ranges a little higher. Some fat is essential for hormones and health, so lower is not always better.