Skinfold Assessment: Body Fat Percentage

This body fat percentage testing method is such a great and inexpensive way to measure someone's body fat. It requires a skinfold Caliper and an experienced technician. EXPERIENCED, meaning you are going to have to practice at least 100 times to get semi-good at this. NoBODY is the same. The only major downside to this method is that it's invasive and many people are not comfortable with you pinching their "fat". Additionally, with the way our population is going, really overfat people will not have accurate readings, so keep that in mind when choosing your method.

Skinfold Calipers

Skinfold calipers are used to measure subcutaneous fat for the prediction of percent body fat. The amount of subcutaneous fat is proportional (approximately 50% of the total body fat).

Percent Error: The standard error for the skinfold prediction is ± 3.5% body fat units (ACSM, 2009).

Skinfold Calipers Procedures:

• All skinfold measurements should be taken on the right side of the body with the subject standing upright.

• After marking the site with a “t” or “x”, the caliper should be placed directly on the skin surface, 1cm away from the thumb and finger, perpendicular to the skinfold, and halfway between the base and the crest of the fold.

• A pinch should be maintained while reading the caliper.

  • Wait 1 to 2 seconds (no longer) before reading the caliper.

• Take duplicate measures at each site, and retest if duplicate measures are not within 1 to 2 mm.

• Rotate through measurement sites, or allow time for skin to regain normal texture and thickness.

• Use the standardized anatomical descriptions for skinfold sites to locate each site. Mark the seven skinfold sites with the marker or pen.

Skinfold Measurement Sites

The Jackson/Pollock (J-P) method uses a nomogram, equations, or tables to estimate body fat percentage from the sum of three OR seven skinfold for each sex.

• The three sites for women are

  • 1) triceps

  • 2) suprailiac

  • 3) thigh 

• The three sites for men are

  • 1) thigh

  • 2) chest

  • 3) abdomen

The seven sites for both men and women include:

1) chest

2) midaxillary

3) triceps

4) subscapular

5) abdomen

6) suprailiac

7) thigh

Standardized Anatomical Descriptions for Skinfold Sites

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Midaxillary:

1. a. Locate and mark the point on the midaxillary line at the level of the xiphoid process of the sternum.

2. b. Grasp a vertical skinfold at a point 1 cm above the skinfold site.

Chest:

1. a. Locate and mark the point half the distance from the anterior axillary fold (the front of the armpit) and the nipple.

2. b. Grasp a diagonal skinfold about 1 cm above the skinfold site (the long axis of the fold towards the nipple).

3. c. Apply the calipers across the fold 1 cm inferior to the grasp.

Triceps:

1. a. Bend the subject’s right arm to a 90 degree angle, keeping the elbow close to the side.

2. b. Locate and mark the midpoint of the top lateral portion of the shoulder (acromion process of the scapula) and the tip of the bent elbow (inferior portion of the olecrenon process of the ulna)

3. c. Instruct the subject to straighten their arm

4. d. Using the thumb and the index finger, grasp a vertical fold at the back of the arm (about 1 cm above the skinfold site).

5. e. Place the calipers at the skinfold site.

Subscapular:

1. a. Locate and mark the site about 1-2 cm below the inferior angle of the scapula.

2. b. Grasp a diagonal skinfold (45° angle) at a point 1 cm above the skinfold site.

Abdomen:

1. a. Locate and mark the site about 2 cm to the right of the umbilicus.

2. b. Grasp a vertical skinfold at a point 1 cm above the skinfold site.

3. c. Place the calipers at the site across the long axis of the skinfold.

Suprailiac:

1. a. Locate and mark the site above the right iliac crest (in line with the natural angle of the iliac crest) in the anterior axillary line.

2. b. Grasp a diagonal skinfold to the marked site.

3. c. Place the calipers across the long axis of the fold

Thigh:

1. a. Flex the subject’s right hip in order to locate the crease between the hip and the right leg

2. b. Locate the anterior groin area of the hip

3. c. Locate the proximal border of the patella

4. d. Locate and mark the midpoint of the anterior-most aspect of the thigh (the midpoint is halfway between the anterior groin area of the hip and the proximal border of the patella)

5. e. Instruct the subject to relax their right thigh muscle by placing all of their weight on the left leg.

6. f. Grasp a vertical fold, with your thumb and index finger, about 1 cm above the skinfold site and place the calipers across the axis of the skinfold site.

Equations

**Round to 4 spaces after decimal point**

Jackson and Pollock 3 Site Method:

DB (Men) = 1.10938 – (0.0008267 * SSF) + (0.0000016 * SSF^2) – (0.0002574 * Age)

SSF= sum of chest, abdomen, and thigh skinfolds

DB (Women) = 1.0994921 – (0.0009929 * SSF) + (0.0000023 * SSF^2) – (0.0001392 * Age)

SSF = sum of triceps, supraillium, and thigh skinfolds

Jackson and Pollock 7 Site Method:

DB (Men) = 1.112 – (0.00043499 * SSF) + (0.00000055 * SSF^2) – (0.00028826 * Age)

DB (Women) = 1.097 – (0.00046971 * SSF) + (0.00000056 * SSF^2) – (0.00012828 * Age)

Once you have the DB number from your calculation above, you will plug that in to the equation below to get your body fat % estimate.

Percent Fat Equation

% Fat = (495/DB) – 450

Reference:

Pescatello, L. S., Thompson, W. R., & Gordon, N. F. (2009). A preview of ACSM's guidelines for exercise testing and prescription. ACSM's Health & Fitness Journal, 13(4), 23-26.