The U.S. Navy formula
The method uses the logarithm of your circumference measurements relative to your height. The measurements go in inches:
Men: %BF = 86.010 · log₁₀(waist − neck) − 70.041 · log₁₀(height) + 36.76
Women: %BF = 163.205 · log₁₀(waist + hip − neck) − 97.684 · log₁₀(height) − 78.387
Enter metric measurements and the calculator converts them to inches first. Add your weight to also see your fat mass and lean (fat-free) mass.
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% |
| Above average | 25%+ | 32%+ |
Measuring tips
Use a flexible tape on bare skin, kept level and snug without compressing. Measure the neck below the larynx, the waist at the navel (men) or narrowest point (women), and the hip at its widest point. Measuring at the same time of day each time makes tracking changes more reliable than any single reading.
Frequently asked questions
How does the Navy body fat method work?
It estimates body fat from tape measurements using a formula developed by the U.S. Navy. Men measure height, neck, and waist; women add the hip. Because fat tends to gather at the waist and hips, those circumferences relative to height predict body fat reasonably well without special equipment.
How accurate is it?
The Navy method is within about 3–4% of a DEXA scan for most people — good enough to track changes over time. It is less accurate for very lean, very muscular, or very heavy individuals. For consistent results, measure at the same time of day with the tape snug but not compressing the skin.
What is a healthy body fat percentage?
For men, roughly 6–24% is typical, with fitness around 14–17%. For women, who carry more essential fat, roughly 14–31% is typical, with fitness around 21–24%. Athletes are often lower. These ranges are general guides, not medical thresholds.
Where exactly do I measure?
Neck: just below the larynx, sloping slightly down to the front. Waist: at the navel for men, at the narrowest point for women. Hip (women): at the widest point. Keep the tape level and snug without squeezing, and measure on bare skin for the best result.
Disclaimer: The Navy method is an estimate, not a medical measurement, and is less accurate at the extremes of leanness or size. It is not medical advice — consult a professional for a clinical body-composition assessment.