A body fat caliper is a hand-held instrument used by health professionals to measure body fat stored subcutaneously, or under the skin. Also known as a skinfold caliper, it may be employed by personal trainers, coaches, or other fitness professionals to assess the amount of subcutaneous body fat a person carries by pinching the skin and fat beneath it at several standardized sites on the body. Body fat calipers are available in both digital and manual models and are used in conjunction with body-weight measurements taken on a scale to determine body composition.
Developed in the 1970s as a simple and inexpensive way to analyze body fat, the skinfold test relies on an equation that factors the caliper measurements in millimeters with weight and age and produces an estimate of body fat percentage. Because the body fat caliper cannot measure visceral fat, or fat stored deep among the organs, it is not 100 percent accurate at gauging body composition. If it is used at regular intervals, however, such as every four to six weeks, it can measure changes in body fat over time with reasonable accuracy.
Human error can affect the results of a body fat caliper test. It is important that the same person perform the test each time. Another variable that can affect reliability of these measurements is whether the individual administering the test pinches the exact same sites with a consistent amount of pressure, as human error can throw off the results.
Testing methods commonly measure three to seven sites on the body and rely on a formula such as the Jackson-Pollock or Durnin-Womersly formula. In the Jackson-Pollock seven-site method, the body fat caliper is used to pinch fat at the triceps, the chest near the armpit, the side of the rib cage, the back at the bottom of the shoulder blade, the abdomen, the top of the hipbone, and the front of the thigh. Each measurement is taken twice for accuracy, and the average of the two measurements is recorded for each site. These numbers are then plugged into the Jackson-Pollock formula, often with the assistance of a web-based body fat calculator, and a number is produced that represents the person’s percentage of body fat. This number is often accompanied by fat mass and fat-free mass, in pounds, as they pertain to the individual’s total body weight.
Body fat calipers are available for purchase online and in some medical retail stores and can vary widely in price. Digital body fat calipers are typically more expensive — the digital version of the Accu-Measure® body fat caliper, from Accu Fitness, sells for $120 US Dollars (USD) — but calculate results immediately. Manual versions such as the Lange skinfold caliper, the exception at $240 USD, can sell for as little as $15 USD and deliver similar accuracy.