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Equations: Jackson & Pollock

Here are several equations that give a value for body density and percent body fat from skinfold and girth circumference test results, from the research of Dr. Andrew Jackson and M. L. Pollock. Once the body density is calculated using the equations below, the level of percent bodyfat (%BF) can be determined using the Siri Equation. See more equations for measuring body fat using skinfold measures.

Males

4-Site Skinfold Equation (for calculating % body fat)

% Body Fat  = (0.29288 x sum of skinfolds) – (0.0005 x square of the sum of skinfolds) + (0.15845 x age) – 5.76377, where the skinfold sites (measured in mm) are abdominal, triceps, thigh and suprailiac
(reference: Jackson A S, Pollock, M (1985) Practical assessment of body composition. Physician Sport Med. 13: 76-90.)

Females

4-Site Skinfold Equation

% Body Fat  = (0.29669 x sum of skinfolds) – (0.00043 x square of the sum of skinfolds) + (0.02963 x age) + 1.4072, where the skinfold sites (measured in mm) are abdominal, triceps, thigh and suprailiac

3-Site Skinfold Equation

% Body Fat  = (0.41563 x sum of skinfolds) – (0.00112 x square of the sum of skinfolds) + (0.03661 x age) + 4.03653, where the skinfold sites (measured in mm) are abdominal, triceps and suprailiac

Males

Equation includes girth measurements

Body Density = 1.0990750 - 0.0008209 (X2) + 0.0000026 (X2)2 - 0.0002017 (X3) - 0.005675 (X4) + 0.018586 (X5). Where X2 = sum of the chest, abdomen and thigh skinfolds in mm, X3 = age in years, X4 = waist circumference in m, and X5 = forearm circumference in m.

3-Site Skinfold Equation

Body Density = 1.10938 - (0.0008267 x sum of chest, abdomen and thigh skinfolds in mm ) + (0.0000016 x square of the sum of chest, abdomen and thigh) - (0.0002574 x age)
(reference: Jackson, A.S. & Pollock, M.L. (1978), based on a sample aged 18-61)

7-Site Skinfold Equation

Body Density = 1.112 - (0.00043499 x sum of skinfolds) + (0.00000055 x square of the sum of skinfold sites) - (0.00028826 x age), where the skinfold sites (measured in mm) are: Chest, Axilla, Tricep, Subscapular, Abdominal, Suprailiac and Thigh
(reference: Jackson, A.S. & Pollock, M.L. (1978), based on a sample aged 18-61)

Females

Equation that includes girth measurements

Body Density = 1. 1470292 - 0.0009376 (X3) + 0.0000030 (X3)2 - 0.0001156 (X4) - 0.0005839 (X5), Where: X3 = sum of triceps, thigh and suprailiac skinfolds, in mm, X4 = age in years and X5 = gluteal circumference in cm.

3-Site Skinfold Equation

Body Density = 1.0994921 - (0.0009929 x sum of triceps, thigh and suprailiac skinfolds) + (0.0000023 x square of the sum of triceps, thigh and suprailiac skinfolds) - (0.0001392 x age)
(reference: Jackson, et al. (1980), based on a sample aged 18-55)

7-Site Skinfold Equation

Body Density = 1.097 - (0.00046971 x sum of skinfolds) + (0.00000056 x square of the sum of skinfold sites) - (0.00012828 x age), where the skinfold sites (measured in mm) are: Chest, Axilla, Tricep, Subscapular, Abdominal, Suprailiac and Thigh
(reference: Jackson, A.S. & Pollock, M.L. (1978), based on a sample aged 18-61)

References

• Jackson, A. S., & Pollock, M. L. (1978). Generalized equations for predicting body density of men. British Journal of Nutrition, 40, 497-504.
• Jackson, A. S., Pollock, M. L., & Ward, A. (1980). Generalized equations for predicting body density of women. Medicine and Science in Sports and Exercise, 12, 175-182.