There are several different protocols to determine body fat percentage. One of the most commonly used is the Jackson-Pollock protocol. This method utilizes an instrument called a caliper to measure skinfolds on different sites of the body. The measurements are taken in millimeters and entered into a final equation to calculate body fat percentage.
Site Skinfold Measurement and Body Composition Calculation
Step 1
Us your pointer finger and thumb to pinch a diagonal fold halfway between the nipple and the armpit. Measure the pinched skin with the caliper and record the result. For women, measure a diagonal fold one-third of the way between the nipple and armpit.
Step 2
Raise the arm and pinch a vertical fold on the midaxillary line about an inch below the nipple. The midaxillary line runs down the body beginning at the armpit. Measure the fold with the caliper and record the result.
Step 3
Let the arm dangle loosely from the body. Perform a vertical pinch on the triceps area, about halfway between the elbow and the shoulder. Use your caliper to measure the fold and record the measurement.
Step 4
Locate the shoulder blade. Pinch a 45-degree diagonal fold 1 to 2 cm below the shoulder blade. Measure with the caliper and record the result.
Step 5
Pinch a vertical fold about one inch to the side of the belly button. Use the caliper to measure the fold and record the result.
Step 6
Locate the iliac crest, or the top of the protruding hipbone. Pinch a diagonal fold directly above the iliac crest and measure with the caliper. Record the result.
Step 7
Locate the halfway point of the knee and top of the thigh on the anterior side of the leg. Pinch a vertical fold and measure with the caliper. Record the measurement.
Step 8
Repeat all measurements on the same side of the body at least two times, preferably three. Record each of the measurements as you go.
Step 9
For men, average the numbers from each skinfold site. Add together the final seven measurements. Insert into the following equation to calculate body density:
1.112 - 0.00043499 (sum of skinfolds) + 0.00000055 (sum of skinfolds)^2 - 0.00028826 (age).
Next, use the number you calculate to find body fat percentage using the following equation:
[(4.95/body density) - 4.5] x 100.
The number you receive is body fat percentage for men.
Step 10
For women, average the numbers from each skinfold site. Add together the final seven measurements. Insert into the following equation to calculate body density:
1.097 - 0.00046971(sum of seven skinfolds) + 0.00000056 (sum of seven skinfolds)^2 - 0.00012828 (age).
Use the number you calculate to find body fat percentage using the following equation:
[(4.95/body density) - 4.5] x 100.
The number you calculate is body fat percentage for women.
Tips and Warnings
- Measure skinfolds on the right side of the body if possible. For the most accurate measurement, place the caliper perpendicularly 1 cm away from the fingers and halfway between the top and bottom of the fold. Continue to pinch until the result is noted. Rotate between sites while acquiring additional measurements.
- Even with proper technique, using skinfolds to calculate body fat percentage is not completely accurate. Assume a plus or minus 3.5 percent error rate while using this protocol.
Things You'll Need
- Caliper
- Paper
- Pencil
- Calculator
References
- "ACSM's Guidelines for Exercise Testing and Prescription"; American College of Sports Medicine; 2000
- "Essentials of Personal Training: Client Consultation and Fitness Assessment"; National Strength and Conditioning Association; 2009
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