How to Calculate Body Fat From Caliper Measurements

Calipers calculate body fat by pulling fat away from muscle. This creates skinfolds. The calipers measure the folds’ lengths at different sites. When using the Jackson-Pollock method — the most accurate — the tester checks three sites. These depend on gender, and they are always taken on the body's right side. After the tester enters the measurements into two equations, he will have a reliable estimate of the subject’s body fat percentage. While it’s possible to test yourself, experts recommend a professional perform this test.

A close-up of a shirtless man measuring his body fat with calipers. (Image: bert_phantana/iStock/Getty Images)

Mark Test Sites for Men

Step 1

Mark the chest fold. This is located halfway between the anterior axillary line, or underarm crease, and nipple. The fold will be diagonal.

Step 2

Mark the abdominal fold. This is located an inch next to the umbilicus or belly button. The fold will be vertical.

Step 3

Mark the thigh fold. This is located on the front part of the thigh, halfway between the groin’s inguinal crease and the knee. This fold will be vertical.

Mark Test Sites for Women

Step 1

Mark the triceps fold. This is located on the back of the arm halfway between the shoulder and elbow. The fold will be vertical.

Step 2

Mark the waist fold. This is located at or above the iliac crest. The fold will be diagonal.

Step 3

Mark the thigh fold. This is located on the front part of the thigh, halfway between the groin’s inguinal crease and the knee. This fold will be vertical.

Test Sites

Step 1

Pinch the skinfold with your left thumb and index finger so the fold is 1 cm above the site.

Step 2

Position the caliper perpendicular to the fold about 1 cm beneath the thumb and index finger.

Step 3

Read the dial to the closest 1/2 mm one or two seconds after you release the trigger. Note this measurement.

Step 4

Take at least two readings at each site. Pause a minimum of 15 seconds between measurements. If they differ by more than 1 mm, take more measurements until you get two readings less than 1 mm apart.

Step 5

Repeat this process at each site.

Calculate Body Density and Body Fat

Step 1

Determine subject's body density using the Jackson-Pollock equation. Body density measures body fat composition, but it's not a body fat percentage. To determine the body fat percentage, calculate body density first. Record subject's age.

Step 2

Enter subject's caliper measurements and age into the Jackson-Pollock formula. For men, body density = 1.10938 - (0.0008267 x the sum of the chest, abdomen and thigh skinfolds in mm) + (0.0000016 x the square of the sum of the chest, abdomen and thigh skinfolds in mm) - (0.0002574 x age). For women, body density = 1.0994921 - (0.0009929 x the sum of triceps, waist and thigh skinfolds) + (0.0000023 x the square of the sum of the triceps, waist, and thigh skinfolds) - (0.0001392 x age).

Step 3

Convert subject's body density to a body fat percentage using the Siri equation. It's the same for men and women: percent body fat = [(4.95/body density) - 4.5] x 100.

Tip

Remember to test skinfolds on the the body's right side.

Warning

For best results, don't take caliper measurements yourself. Consult a professional. Avoid cheap calipers. Don't take measurements following exercise due to fluid variation.

REFERENCES & RESOURCES
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