A Step-by-Step Guide to Measuring Body Fat With Calipers

Since too much or too little body fat can come with serious health problems, it's a good idea to know how much you have. While there are several methods, measuring body fat with calipers is among the easiest and most accurate done by health and fitness professionals.

It's best to call on a professional, such as a certified personal trainer, when using calipers to measure body fat.
Credit: Dusan Ilic/iStock/GettyImages

Here's how calipers estimate your body fat, their pros and cons and everything you need to know about actually taking and calculating the measurements.

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How Do Calipers Work?

The skinfold method using calipers, according to the American Council on Exercise (ACE), is the most commonly used method of estimating a person's body composition. A caliper is a tool that measures skinfold thickness at various parts on the body. Measurements are taken by grasping — with the thumb and index finger — a fold of skin and any accompanying subcutaneous (soft) fat, and pulling the skin away from the muscle. The skin is then pinched with the caliper, and the reading is taken within 2 seconds.

When using the Jackson-Pollock method, which is considered the most accurate, the tester checks three sites. These depend on the person's sex and they are always taken on the body's right side. (More on that later.)

After entering the site measurements into two separate equations, the tester will have a reliable estimate of the subject's body fat percentage. And while it's possible to test yourself, it's recommended that a professional perform this test for the most accurate result.

Read more: Why Some Types of Body Fat Are Healthier Than Others

Timing Is Everything

Measurements taken after exercise could lead to overestimations because of the transfer of fluid to the skin, so it's best to take caliper measurements before physical activity.

"The best time to use a body fat caliper is first thing in the morning, before eating, drinking, working out or showering. It is a good idea to repeat the measurements at the same time of day under the same conditions," Amanda Mancini, a National Academy of Sports Medicine (NASM)-certified fitness trainer, weight-loss specialist and corrective exercise specialist, tells LIVESTRONG.com.

The Good and the Bad

Like most things, there are advantages and disadvantages to using fat calipers to measure body fat.

The main advantages are:

  • They're inexpensive
  • They're easy to use (by a well-trained professional)
  • Taking measurements is not time-consuming
  • They're non-invasive
  • They produce fairly accurate results (the standard error is 3.5 percent, depending on the equation used, per the ACE)

The disadvantages, which can lead to errors in reliability, validity or both, include:

  • Variability between technicians (it is recommended that the same professional take your measurements consistently)
  • Variability between sites measured on the body
  • Different equations can be used
  • Readings may not be accurate on people who are either very lean or obese
  • Cheaper calipers typically provide less accurate measurements

Another disadvantage, detailed by a study published September 2015 in Collegium Antropololgicum, is that calipers measure compressed fat and double layers of skin, reducing the precision of the results, compared to the more accurate lipometer — a computerized optical device.

"If not done properly, body fat calipers can be inaccurate," says Mancini. "I believe the best way to measure your body fat is with a tape measure, where you can see the changes in areas of the body that are increasing or decreasing in size."

Want a simple way to estimate your body fat percentage, no formulas required? Plug your measurements into LIVESTRONG.com's Body Fat Calculator.

Measurement Sites for Men

  1. Chest: This diagonal fold is taken halfway between the anterior axillary line, between the crease of the armpit and nipple.
  2. Abdomen: The fold is vertical and located an inch from the belly button.
  3. Thigh: This vertical skinfold is measured on the front part of the thigh, halfway between the hip and the knee.

Measurement Sites for Women

  1. Triceps: A vertical fold is taken on the back of the arm, halfway between the shoulder and elbow. A helper will be needed to get the pinch.
  2. Suprailium: This skinfold is diagonal and located at the ridge of the hip bone (the iliac crest).
  3. Thigh: This vertical fold is measured on the front part of the thigh, halfway between the hip and the knee.

How to Get Accurate Caliper Measurements

  1. Pinch the skinfold with your left thumb and index finger so the fold is 1 centimeter above the site.
  2. Position the caliper perpendicular to the fold, about 1 centimeter beneath the thumb and index finger, then press on the thumb pad.
  3. Read the dial two seconds after you release the trigger. Note this measurement.
  4. Take at least two readings at each site but wait a minimum of 15 seconds between measurements. Take the average of the pinches.

Plug in Those Measurements

To determine body fat percentage using these measurements, you'll first need to calculate body density using the Jackson-Pollock equation:

1. Enter the person'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 millimeters) + (0.0000016 x the square of the sum of the chest, abdomen and thigh skinfolds in millimeters) - (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).

2. Convert body density to a body fat percentage using the Siri equation, which is the same for men and women:

  • Percent body fat = [(4.95/body density) - 4.5] x 100

All this math can be tricky, so keep in mind that there are always online calculators to help you figure it all out.

Read more: How to Estimate Your Body Fat Percentage

Body Fat Percentages: What’s the Norm?

Body fat percentages are classified, according to ACE, as essential, athletic, acceptable or obese. Women usually have a higher amount of body fat than men in order to maintain menstruation and have children, so there are different ranges between the two sexes.

Essential

  • Women: 10 to 13 percent
  • Men: 2 to 5 percent

Athletic

  • Women: 14 to 20 percent
  • Men: 6 to 13 percent

Fit

  • Women: 21 to 24 percent
  • Men: 14 to 17 percent

Acceptable

  • Women: 25 to 31 percent
  • Men: 18 to 24 percent

Obese

  • Women: over 32 percent
  • Men: over 25 percent

Read more: How to Lose Body Fat: The Science-Backed Ways That Actually Work

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