The Clinical Caliper Method
While the Navy tape measure method relies on circumferences, the Skinfold Caliper Method physically measures the actual thickness of subcutaneous fat (the fat stored directly beneath the skin).
Using specialized calipers to "pinch" the skin, this method is considered the gold standard for personal trainers and exercise physiologists outside of a laboratory setting.
The Jackson-Pollock Equations
Developed in 1978 by Dr. Andrew Jackson and M.L. Pollock, the 3-Site Skinfold formula revolutionized fitness testing. They discovered that measuring just three specific sites on the body could accurately predict total overall body density.
Because men and women store fat in entirely different biological patterns, the specific sites measured differ by gender.
The Formula
The sum of the three pinch sites (in millimeters) is run through a quadratic equation to determine body density. That density is then converted into a final body fat percentage using the famous Siri Equation.
BF% = (495 / Body Density) - 450
The Measurement Sites
- Men: Chest (diagonal fold), Abdomen (vertical fold), Thigh (vertical fold).
- Women: Triceps (vertical fold), Suprailiac/Hip (diagonal fold), Thigh (vertical fold).