About the Body Fat Calculator
Body fat percentage tells you more about health and fitness than weight or BMI alone, because it separates fat from muscle, bone and water. This calculator uses the U.S. Navy method (Hodgdon and Beckett, 1984), the same circumference formula the U.S. military uses for body composition checks.
The result is placed on the American Council on Exercise (ACE) scale, and with your weight it also shows how many pounds or kilograms are fat and how many are lean mass.
How to use
- Choose your sex and units (inches and pounds or cm and kg).
- Measure your neck just below the larynx, and your waist at the navel. Women also measure the hips at their widest point.
- Enter height, weight and the measurements. Your body fat percentage, category, fat mass and lean mass appear right away.
U.S. Navy body fat formula
With measurements in centimeters:
Men: %BF = 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450
Women: %BF = 495 ÷ (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450
Example: a man 175 cm tall with a 38 cm neck and an 85 cm waist has about 16.9% body fat.
Body fat chart (ACE)
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25% and up | 32% and up |
Women naturally carry more essential fat than men, so the ranges are higher.
FAQ
How accurate is the Navy body fat method?
Compared with DEXA scans, it is usually within about 3–4 percentage points. Careful, repeatable measuring matters more than anything else: same time of day, same tape, same spot.
What is a healthy body fat percentage?
Roughly 14–24% for men and 21–31% for women falls in the fitness to average range. Ideal values also depend on age.
What is lean body mass?
Everything that is not fat: muscle, bone, organs and water. It is your weight minus your fat mass.
Is this a medical assessment?
No. It is an estimate for general information. For an accurate body composition analysis, ask a doctor or use a clinical method such as DEXA.