Using a high-quality professional tool called a caliper, a trained tester typically measures body fat at 3 to 9 sites on the body. The tester first pinches the skin and the fat that lies under the skin and pulls the skin and fat away from the muscle. The tester then places the caliper 1 cm (0.4 in.) above or below the pinch and reads the measurement from the caliper dial. Usually about two or three measurements are taken at each site.

Body fat measurements can vary depending on who takes the measurement. To see if your body fat level has changed, it’s best to get measured by the same person.