Calculate Your Body Fat
Men: waist at the navel. Neck just below the Adam's apple.
How to Measure
- Neck: just below the larynx (Adam's apple), with the tape sloping slightly down toward the front.
- Waist (men): horizontally at the navel, at the end of a normal breath out.
- Waist (women): at the natural waist, the narrowest point between the ribs and hips.
- Hips (women): at the widest point of the buttocks, feet together.
- Keep the tape snug but not compressing the skin, and take each measurement twice.
- Use a tape that doesn't stretch. See our tape measure picks →
The Formulas
These are the widely used inch-based forms of the Hodgdon and Beckett (1984) Navy equations (log base 10):
Men: %BF = 86.010 × log(waist − neck) − 70.041 × log(height) + 36.76
Women: %BF = 163.205 × log(waist + hip − neck) − 97.684 × log(height) − 78.387
Metric entries are converted to inches before calculating.
Body Fat Categories
| 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 |
Categories follow the American Council on Exercise (ACE) chart. For military follow-up limits by branch, see military standards by branch.
Tape-based equations can be off by several points, especially for very muscular or very lean people. Track the trend over time and talk with a clinician about your health.
Frequently Asked Questions
How accurate is the Navy tape method?
In the original Navy studies, tape estimates typically landed within about 3 to 4 percentage points of underwater weighing. It works best for people of average build and tends to be less accurate for very muscular or very lean people.
Where should I measure my waist for this calculator?
Men measure the waist at the navel. Women measure at the natural waist, the narrowest point of the torso, plus the hips at the widest point of the buttocks. The neck is measured just below the Adam's apple.
Is this the same test the military uses?
It uses the classic Navy circumference equations. Military services now screen with waist-to-height ratio first, and each branch uses its own approved body fat method for follow-up, so your official result may differ.
What is a healthy body fat percentage?
Commonly cited fitness ranges are about 14% to 17% for men and 21% to 24% for women, with “average” running up to about 24% for men and 31% for women. Health risk depends more on where fat is stored, which is why waist-to-height ratio is a useful second check.
Check Your Waist-to-Height Ratio Too
Body fat tells you how much; waist-to-height ratio tells you where. Get both pictures in one minute.
Open TrueFit BMI Calculator →📚 Sources
- Hodgdon, J. A., & Beckett, M. B. (1984). Prediction of percent body fat for U.S. Navy men from body circumferences and height (Report No. 84-11). Naval Health Research Center.
DTIC (PDF) → - Hodgdon, J. A., & Beckett, M. B. (1984). Prediction of percent body fat for U.S. Navy women from body circumferences and height (Report No. 84-29). Naval Health Research Center.
DTIC (PDF) → - American Council on Exercise. Percent body fat norms for men and women.