Measuring skinfolds using calipers is the most popular method for determining body fat percentage, according to the Department of Kinesiology and Health at Georgia State University. Calipers are inexpensive and easy to use, relative to other methods such as underwater weighing. Measure the skinfold thickness at four sites for females---the abdomen, the suprailiac, or just above the hip bone, the thigh and the triceps. Include the same sites for males, but add the chest, the midaxillary, or under the armpit, and the area just below the scapula bone, known as the subscapular. After taking the measurements, use a reliable formula to calculate your body fat percentage.
Step 1
Pinch a fold of skin between your thumb and index finger at all the designated areas of your subject. Fold the skin vertically at the abdomen, subscapular, thigh and triceps, and diagonally at the chest, midaxillary and suprailiac.
Step 2
Pull the skinfold away from the body slightly, separating it from the muscle which lies underneath the layer of fat.
Step 3
Continue grasping the skinfold and hold the caliper in your opposite hand. Open the pincers and place them on either side of the skinfold, just below your thumb and index finger. Close the pincers on the skinfold.
Step 4
Read the caliper within 2 seconds after closing the pincers for an accurate measurement. Record the measurement on paper.
Step 5
Repeat steps 1 through 4 twice more to make sure you read the measurement correctly. Find the average of your measurements by adding them together and then dividing the answer by 3. For example, if you read 27 mm for the first trial, 28 mm for the second, and 28.5 mm for the third, the average is (27 + 28 + 28.5) ÷ 3, or 27.8.
Step 6
Add together the measurements from all the areas of the body. For example, if you determine measurements of 33 mm, 34 mm, 21 mm and 22 mm from the abdomen, suprailiac, thigh and triceps, respectively, of a female subject, add 33 + 34 + 21 + 22, which equals 110 mm.
Step 7
Calculate the body density of your subject, in grams per cubic centimeter, using the following formula for females: 1.096095 -- (0.0006952 --- sum of skinfolds) + (0.0000011 --- sum of skinfolds squared) -- (0.0000714 --- age). Continuing with the example from above, assuming the subject is 25 years old, her body density is 1.096095 -- (0.0006952 --- 110) + (0.0000011 --- 12100) -- (0.0000714 --- 25), or 1.031148 g per cc. Use a slightly different formula for male subjects: 1.112 -- (0.00043499 --- sum of skinfolds) + (0.00000055 --- sum of skinfolds) -- (0.00028826 --- age).
Step 8
Convert body density to body fat percentage using the following formula for females: [(5.01 ÷ body density) -- 4.57] --- 100, and the following formula for males: [(4.95 ÷ body density) -- 4.5] --- 100. Using the same example, the female subject has a body fat percentage of [(5.01 ÷ 1.031148) -- 4.57] --- 100, which equals 28.9 percent when rounded to the nearest tenth.
Tips and Warnings
- Practice taking skinfold measurements often to improve your ability to position the caliper properly and read the measurement quickly.
- Skinfold measurements are subject to human error and may be inaccurate, especially for very obese and very lean individuals.
Things You'll Need
- Calculator
- Paper
- Pencil
References
- "Sports and Exercise Nutrition (Third Edition)"; William D. McArdle, Frank I. Katch, and Victor L. Katch; 2009
- Georgia State University: The Exercise and Physical Fitness Page
- Accu-Measure: The Ideal Way To Measure Body Fat
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