Body Fat Calculator (Navy Method)
The US Navy body fat method estimates your body fat percentage from a few tape measurements instead of calipers or a lab scan. It is circumference-based, meaning it reads body fat from the size of your neck, waist, and hips rather than from a skinfold pinch, which makes it easy to repeat at home on your own.
Validated against skinfold testing, the Navy method typically lands within roughly 3 to 4 percent of those readings for most people. All you need is a flexible tape measure and your measurements taken at the right spots: neck, waist, height, and hips for women. Take each measurement snug but not compressing the skin for the most consistent result.
How the Navy formula works
The Navy method uses two formulas, one per sex, with all measurements in inches. For men: body fat % = 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76. For women: body fat % = 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387. The women formula adds the hip measurement because fat distribution differs, so the extra circumference improves the estimate.
Measure your neck just below the larynx (the Adam's apple), keeping the tape slightly downward to the front. Measure the waist at the navel for men and at the narrowest point of the torso for women. Measure hips at the widest point around the glutes. Round each measurement to the nearest half inch and keep the tape level and snug rather than tight.
How accurate is it
The Navy method is an estimate, not a lab measurement. Compared with a DEXA scan, the gold standard for body composition, circumference methods are typically accurate to within about 3 to 4 percent for people in a normal range, and they read less reliably at the extremes: very lean athletes and people carrying more fat both tend to see larger errors.
Its strength is consistency over time. Because you measure the same spots the same way, the trend it shows as you cut or gain is more useful than any single reading. For an absolute number, a DEXA scan or hydrostatic weighing is more precise, but for tracking progress at home the tape is hard to beat.
Frequently asked questions
Where do I measure my waist for the Navy body fat test?
Men measure at the navel, and women measure at the narrowest point of the torso, usually just above the belly button. Keep the tape horizontal and snug against the skin without compressing it, and measure at the end of a normal exhale for a repeatable reading.
How accurate is the Navy body fat formula?
It is typically within about 3 to 4 percent of a DEXA scan for people in a normal body fat range. Accuracy drops at the extremes, so very lean or heavier individuals may see larger errors, but the method is reliable for tracking your trend over time.
What is a healthy body fat percentage?
For men, roughly 14 to 24 percent is a common healthy range, with athletes often at 6 to 13 percent. For women it runs higher due to essential fat, roughly 21 to 31 percent healthy and 14 to 20 percent for athletes. These are general guidelines, and individual health depends on more than one number.
Do I need to be fasted or dehydrated to measure?
No. The Navy method reads circumferences, not water weight, so fasting or dehydrating is unnecessary and can skew results. For consistency, measure at the same time of day under the same conditions, such as first thing in the morning before eating.