How to use skinfold thickness to determine body fat percentage
The skinfold measurement test is one of the oldest and still most common methods of determining a person’s body composition and body fat percentage.
This test estimates the percentage of body fat by measuring skinfold thickness at specific locations on the body. The thickness of these folds is a measure of the fat under the skin, also called subcutaneous adipose tissue. Skinfold thickness results rely on formulas that convert these numbers into an estimate of a person’s percentage of body fat according to a person’s age and gender.
Skinfold measurements are generally taken at specific sites on the right side of the body. The tester pinches the skin at the location site and pulls the fold of skin away from the underlying muscle so only the skin and fat tissue are being held. Special skinfold calipers are then used to measure the skinfold thickness in millimeters. Two measurements are recorded and averaged.
The measurement sites vary depending upon the specific skinfold testing protocol being used, but typically include the following seven locations on the body:
- Triceps – The back of the upper arm
- Pectoral – The mid-chest, just forward of the armpit
- Subscapular – Beneath the edge of the shoulder blade
- Midaxilla – Midline of the side of the torso
- Abdomen – Next to the belly button
- Suprailiac – Just above the iliac crest of the hip bone
- Quadriceps – Middle of the upper thigh
Formula For Calculating Percent Body Fat from Skinfold Measurements
Once you have taken skinfold measurements, you’ll need to convert these numbers into a percent of body fat.
The easiest way to calculate the percent of body fat is to use a software program. There are as many different formulas and calculations as there are ways to measure skinfold thickness, but some that have held up over time include those published by Jackson and Pollock. You can find these being used in the following online body fat calculators:
- Body Composition Calculator 1
- Body Composition Calculator 2
Are Skinfold Measurements of Body Fat Accurate?
According to the American College of Sports Medicine, when performed by a trained, skilled tester, skinfold measurements of body fat are up to 98% accurate. For this reason, it’s important to find a qualified expert if you have a skinfold measurement done. The accuracy of these tests may also depend on the type of calipers being used and a person’s level of hydration at the time of the test. Most importantly, even if the accuracy is somewhat off, if you have the test done by the same tester under similar conditions, you may find the test a useful way to determine body composition change over time.
With the newer technologies available, skinfold testing is becoming somewhat of an ancient art-form. Most personal trainers today use electrical impedance methods and scales that measure body composition instead of directly measuring skinfolds. Whichever method you use, it’s important to keep in mind that weight fluctuates constantly and most body composition tests should be used as a general reference point and are best when averaged over a given timeframe.