Want a body composition estimate without buying calipers or booking a DEXA scan? The Body Fat Percentage Calculator uses the U.S. Navy circumference method — just a tape measure and a few simple measurements.
How the Navy method works
The U.S. Navy developed this formula as a practical, field-expedient alternative to hydrostatic weighing for military fitness assessments. It estimates body fat percentage from a logarithmic relationship between your neck and waist circumference (plus hip circumference for women) relative to your height:
- Men: uses neck, waist, and height
- Women: uses neck, waist, hip, and height (research found the female formula needs the extra hip measurement to stay accurate, since body fat distribution differs by sex)
Getting an accurate measurement
The most common source of an inaccurate result isn’t the formula — it’s measuring at the wrong spot. Measure your waist at navel level (not your narrowest point) and your neck just below the larynx, holding the tape snug but not compressed.
How accurate is it really?
This method is a reasonable estimate — typically within a few percentage points for most body types — but it’s less precise than DEXA scans or professionally-administered skinfold calipers. Treat the result as a useful general estimate for tracking trends over time, not a clinical diagnosis.
Try it yourself
Enter your measurements on the Body Fat Percentage Calculator in metric or imperial units, and get an instant estimate with a fitness category.