Which is the most accurate test to measure body fat?

Before you start going on a diet in an attempt to become healthy by minimizing your weight, or you are simply planning to become an athlete, you first require an understanding of what makes your weight “unhealthy”.

In some scenarios, people assumed to be overweight might be healthier than some people considered possessing normal weight. Similarly, people whose weights are perceived as normal might not be doing so well with regards to health. Why is that? It’s because they may have the components required to make their weight unhealthy and that component is usually fat.

Controlling the number of fats is much more essential if the end goal is to be healthier and the first step to controlling anything is measuring its current quantity and identifying the area where it’s located.


A variety of ways exist that measure body weight. These techniques differ in their methodology, accuracy, and benefits. Some most accurate techniques to measure body fats are discussed below.

Body fat scale

These scales use a technology known as bioelectrical impedance analysis (BIA). An electric current is passed through one leg, up to the pelvis, and comes down from the other leg. Since fat conducts less electricity than the water and muscle present in your body, therefore the scale records more body fat when it faces more resistance. Its accuracy depends on different variables such as

  • Hydration level
  • Last meal
  • Timing of exercise.

With accuracy dependent on such variables, scales may not give accurate results. They may also differ in accuracy for different age groups, diseases such as osteoporosis, athletes.

Air displacement plethysmography

This uses the same method as hydrostatic weighing. It uses air instead of water for body weight testing. A person enters a BOD POD undressed which totally encloses the person’s body. After determining body density through weight and volume of the body, the machine calculates body fat percentage. Research proves BOD POD to be insanely accurate as it matches the accuracy of underwater measurement which is within 1 percent of body fat for all ages.

MRI or CT scans

Magnetic resonance imaging (MRI) or computerized tomography (CT) scans are considered to be the most accurate method for determining body fat percentage. Cross-sectional images of the body are taken by the use of these machines. Even intra-abdominal fat can be measured. These tests are often used for medical purposes. They are also quite expensive.


A tool known as calipers is used to pinch different areas of your body and thus measure body fat. This is known as a skin-fold test. Usually people tend to go with a three-site approach developed by researchers Jackson and Pollock in the 1980s. It is time efficient as well as cost effective.

Men are required to measure fat present in their chest, abdominals and thighs while women are required to measure fat at their triceps, suprailiac and thighs. Instructions may be available along with calipers that enable the user to convert the numbers into their body fat percentage. However a skin-fold calculator can also be consulted for such a purpose. For consistency, take measurements on one side of the body. Pinch site is to be marked 1 centimeter above the skin-fold.

At the very least two measurements should be taken and then averaged to attain accuracy. If performed correctly, there would be a three percent error rate. In order to improve accuracy, a seven-site measurement can also be done which is more time consuming and slightly increases its accuracy. Gym members hire a personal trainer to take measurements for them.

Hydrostatic Weighing

This is where Hydrostatic Weighing or Hydrostatic Testing comes in, a technique based on Archimedes Principle. It is one of the most accurate ways to measure body weight and is considered to be a gold standard for body composition measurements. In case you missed your classes or did not pay attention to your lectures, we shall be recalling Archimedes Principle which states that if a body is completely or partially submerged in a fluid, the volume of the fluid displaced is equal to the volume of the entire body or part of the body that is submerged.

In Hydrostatic Weighing, the body’s weight is measured underwater and is compared with the bodyweight measured inland. The difference between the two weights enables test administrators to calculate your body density and fat percentage accurately. As muscles are dense, therefore they sink while fat floats due to less density as compared to muscles. Hence a person with high amounts of fat will float whereas a person with more muscle will weigh more underwater. Hydrostatic Weighing is usually used in circumstances where accurate and precise measurement is required.


The Hydrostatic Weighing procedure requires the person to not eat or exercise at least 4 hours beforehand. During this procedure:

  • Body weight on land is measured.
  • The person is then entered in an underwater tank with an underwater seat hanging from a scale.
  • While sitting on the chair, you are completely submerged underwater and you are required to breathe out completely and to remain motionless while underwater weight is measured.
  • The test is repeated three times.

The average of the tests conducted is compared with body weight on land and thus your body fat percentage is calculated. Special calculation is used to determine lean weight and fat weight and determine body fat percentage. Fat weighs less than muscle and both displace a specific amount of water.


  • This method of body composition analysis is considered to be very accurate in determining body fat.
  • It can be performed under 15 minutes thus proving to be time efficient.
  • When we undergo testing perfectly, the error of this device can be as low as 2% body fat.
  • The accurate determination of body fat allows us to create better diets and fitness programs targeting specific problematic areas thus improving health and well being.


  • One limitation is that the person administering the test needs to understand the principles and do the calculations correctly.
  • A source of error in the test is the need to get all air out of the subject’s lungs when weighing underwater, as any air remaining will make them float and throw off the results. This is one of the main reasons that three underwater weights are taken and averaged.
  •  It can also be quite stressful for some people due to not being able to hold their breath. It is also highly costly.
  • While accurate, it does not tell us where the harmful fat is located thus making it difficult to identify what sort of diet and exercises are the most optimum.
  • Due to the difference in bone composition caused by osteoporosis and other bone-related issues, hydrostatic weighing may not show accurate readings.

Why is the hydrostatic weighing test is most accurate to measure body fat:

Now you may ask why you should opt for a hydrostatic weighing procedure when other procedures such as CT and MRI scans can be used to determine the body’s composition?

Well, that’s because hydrostatic weighing is the most accurate test to measure body fat and its accuracy can be up to 1.8 to 2.8 percent compared to other modern methods.

MRI scans can be damaging to artificial pacemakers so those of u implanted with metals aiming to become athletes will find hydrostatic weighing as not only an accurate but also safe for determining the body fats in your body.

We have Skinfold Calipers, a simpler method to calculate body fat. It can be accurate up to 3 to 4 percent but only for 70 percent of the population. Also when administered by somebody inexperienced, they can be significantly less accurate.

Another method is DEXA (Dual-energy X- absorptiometry). While considered gold standard for measuring bone mineral and mineral density, it’s not as accurate as hydrostatic testing for measuring body fat. However, it does tell us where the fat is located which is a limitation of hydrostatic tests.

A common one found on bathroom scales is BIA (bioelectrical impedance analysis). The accuracy of these varies on different factors such as brands, user’s hydration level. Generally, commercially available scales are less accurate and only provide a rough estimate of body composition.

Where to get a Hydrostatic underwater test to measure body fat?

So, after knowing all about hydrostatic weighing; you want to take a test? if you want an accurate and inexpensive body fat test. Get yourself a Hydrostatic body fat test from Get Tanked Li which is located on a long island, 1626 Locus Avenue, Bohemia, NY.

You can book an online appointment. This will save you some time as well. A receptionist will receive your appointment details and will further guide you about the timings.

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