Using the US Navy Body Fat Calculator

This calculator (see bottom of page) uses the U.S. Navy Circumference Method, a simple and quick method that has been shown to be as accurate as skinfold caliper tests, but with a lower standard error of estimation.
Formulae developed by Hodgdon and Beckett at the Naval Health Research Center (1) take into account differences in the way men and women accumulate fat, thus different measurements are required.

How to measure
Measurements within 0.5 cm or 1/4 inch are required. The tape should be tight, but not compress the skin

  • Waist:
    • Men: measure horizontally, at the level of the navel, which roughly coincides with the hip. Note this is not the minimum circumference.
    • Women: measure horizontally, at the level of minimal abdominal width
  • Neck (both): measure below the larynx with the tape sloping slightly downward to the front.
  • Hips (Women only): Largest horizontal circumference around the hips
Places where to measure male circumferrences for the bodyfat calculation after the US-Navy formulaPlaces where to measure female circumferrences for the bodyfat calculation after the US-Navy formula

Body fat
The American Council on Exercise uses the following categories based on percentage of body fat: 

Essential fat   10-12%2-4%
Obese32% or more26% or more

BMI is simply is the ratio of your weight to the square of your height, with ranges falling under 4 categories. While widely used, it has its limitations - is does not diferentiate by gender, and does not consider fat/muscle ratios. If your BMI is 25 or greater, your waist/height ratio is less than 0.5 and % body fat falls within the  "athlete" or "fitness" categories, you are probably muscular and not fat.

UnderweightBMI less than 18.5
Normal weightBMI 18.5 to 24.9
OverweightBMI 25 to 29.9
ObeseBMI 30 or greater

Body Fat Formulae

MenPercentage of Fat = 495 / (1.0324 - 0.19077 x (LOG10(waist - neck)) + 0.15456 x (LOG10(height))) - 450
WomenPercentage of Fat = 495 / (1.29579 - 0.35004 x (LOG10(waist + hip - neck)) + 0.22100 x (LOG10(height))) - 450
MenPercentage of Fat = (86.01 x LOG10((waist) - (neck))) - (70.041 x LOG10(height)) + 36.76
WomenPercentage of Fat = (163.205 x LOG10((waist) + (hip) - (neck))) - (97.684 x LOG10(height)) - 78.387

(1) Hodgdon, J. and Beckett, M. Prediction of percent body fat for U.S. navy men and women from body circumferences and height. Reports No. 84-29 and 84-11. Naval Health Research Center, San Diego, California 1984

Thanks to for provision of JavaScript and formulae.