How Can I Calculate Percent Body Fat with Skinfold Measurements?

Body Fat Calculator Based on Skinfold Measurements
Sex	Male Female
Pectoral	mm
Midaxillary	mm
Tricep	mm
Subprailiac	mm
Abdominal	mm
Thigh	mm
Subscapular	mm
Age	years

Body Density
Percent Body Fat	%

There are many methods of measuring the percentage of fat in a person's body. One of the most widely used formulas calculating percent body fat is one developed by Jackson, Pollack, and Siri et al. It uses 7 skinfold measurements taken with calipers. If you have taken measurements of the thickness of fat under your skin, you can plug these numbers into the formula below. It will yield a fairly accurate percent body fat calculation, within +/- 3%.

The body fat formulas for men and women differ slightly; both are described below. You can also use the body fat calculator on the left.

First, use calipers to take skinfold measurements on 7 areas of the body: pectoral, midaxillary, tricep, subprailiac, abdominal, thigh, and subscapular. The measurements will be in millimeters. Add these 7 numbers and call this sum "F." Call your age "A."

We will use A and F to calculate a number called "body density," or BD for short. The formula for male body density is

BD = 1.112 - (0.000435)F + (0.00000055)F² - (0.000288)A,

and the formula for femal body density is

BD = 1.097 - (0.00047)F + (0.00000056)F² - (0.000128)A.

Next, use the body density value to calculate your percent body fat. Again, these formulas differ for males and females.

% body male fat = 495/BD - 450

% body female fat = 496/BD - 451

Sample computation: Maggie is a 40 year old female who obtained the 7 skinfold measurements, and calculated that F = 113. Using the values A = 40 and F = 113, she computes that BD = 1.0459 and percent body fat = 23.22%.

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