How to Measure Body Fat Percentage?

Feb 26 2020

How to Measure Body Fat Percentage?

Body fat percentage is the proportion of total weight that is fat.

The number is calculated by simply dividing the sum of fat pounds (fat mass) by body weight.

Use the resources below to learn how to find body fat estimates for you.

Why Track Body Fat?
First, click here to learn why it's so crucial that you track your body fat on a regular basis and why your weight is just another number without it.

Online Body Fat Percentage Calculator
Click here to learn how to determine body fat percentage yourself. Please note that this is not the most accurate testing method, but an easy solution for those wanting to take it independently or who prefer to do so in the privacy of their home.

Body Fat Chart By Ace
Click here to see where you and others rank on this body fat index chart.

Body Fat Chart Based on Age
Click here to see where your body fat percentage should be based on age and gender.

Women and Men's Body Fat Differences
Start here to lean about the differences between men and women's body fat ranges and why they should track differently.

Body Fat Percentage Tests
Click here if you would like to learn the current and best methods for body fat testing.

Tests, Costs & Accuracy: How to Work Out Your Body Fat Percentage

There is no absolute way to determine exact body composition on living people.

The current methods have evolved after years of testing and are based on clinically significant relationships between at least one measurable variable that correlates with body composition.

Let's use a pinch test for a basic example.

The thickness of your skin in measured at specific spots on your body with calipers. Those measurements (variables) are then plugged into an equation that has been found to scientifically correlate with body comp. Your body fat is then estimated based on those numbers.

  • Keep in mind that there is a lot of variance in the equations that can be applied. For that reason, you should use an equation that makes the most sense for your lifestyle and situation.
  • For example, if you are not an athlete, you should not use the same equation as they do for calculating body fat.

The proceeding info will help you figure out which method is ideal for your specific needs.

Keep in mind that every testing procedure has advantages and disadvantages.

You will find the variety of ways to track your body fat outlined below.


Special calipers are used to measure folds of skin around specific spots on the body.

This is not a precise method; but it is relatively accurate if a training professional conducts the test.

Unfortunately, there is a variety of formulas that can be used to estimated body fat and quite often it is performed slightly different by each person.

Thus, to increase accuracy, always have the same individual perform your pinch test.

Also, always remember, the pinch test is not an exact measure of your real body fat percentage but can work wonderfully for a monthly reference to monitor your progress. 

Accuracy: Moderately accurate when conducted by a trained professional.

Starting Cost: $10 to $20

Convenience: Widely available at health clubs and only takes a few minutes.

All The Gritty Details: Using hand-held calipers that apply a specific pressure, the skinfold thickness is measured at several locations on your body.

Your body fat percentage is then calculated using the sum of the measurements.

This method is used expecting that the thickness of fat just underneath the skin matches a constant measurement of total body fat, and that the areas selected for measurement exhibit the average thickness of fat underneath the skin.

These measurements are taken by holding the skin and underlying tissue and shaking it to leave out any muscle and pinching it with the calipers. Multiple readings should be made at each site to improve accuracy of the measurements.

  • For the most part, skinfold measurements are very easy to do, inexpensive, and can be done anywhere.
  • Overall, the results can be inconsistent as accuracy entirely depends on the skill of the person taking the measurements as well as the locations used for measurement.
  • The calipers should be in good condition and be capable of maintaining a sustained pressure.
  • The more obese the individual, the more skillful the caliper operator will have to be due to the increased difficulty of pinching the skinfold correctly.



A trained technician connects electrodes to your hand and foot while you lie down.

Then a harmless radio-frequency pulse is run directly through the body to measure water content.

That number provides an estimate of body fat with an error of 2 or 2 1/2 percentage points.

Although, exercise and different levels of liquid intake directly before the test can distort results. 

Accuracy: Equal to the pinch test

Starting Cost: $25

Convenience: It takes only a few minutes and is found at some health facilities.

All The Gritty Details: Impedance of the body is a measurement system that sends a harmless electric current through the body to access body composition.

  • It works because fat and muscle have different percentages of water.
  • There is 70-75 percent in muscle, while there is only 10-20 percent in fat.
  • Coupled with a person's height, weight, gender and age, body fat is calculated.

BIA has gained popularity because it's simple, cost efficient, easy to replicate and non-invasive.

Hydration levels can also distort the accuracy of this test. For that reason, researchers are creating new ways to address fluctuations in subject's different hydration ranges.

Multi-point placement of electrodes on different areas of the body for example has helped to improve measurement accuracy.

BIA does have drawbacks.

  • Results can be thrown off by hydration levels as the testing procedure assumes everyone is at normal levels.
  • Inaccuracies arise when a person is dehydrated, and the test will overvalue body fat.
  • For the best results, BIA should be conducted during the same time daily while you are properly hydrated.
  • Try limiting any other variables that may change your hydration levels when you took the test first for the best results.
  • You goal should be consistency.



Bioelectrical impedance analysis on a bathroom scale can be done from the privacy of your home in a minute or less.

It's the most convenient and realistic procedure for most body comp trackers.

Many scale manufactures now even include an optional bioelectrical impedance analysis (BIA) upgrade on their machines.

You jump on a scale, wait for the numbers and presto, there is your determined body fat.

While standing, bioimpedance is conducted when your bare feet make contact with electrodes on top of the scale.

  • First weight is measured followed by impedance.
  • Most electric scales have preprogrammed setting to simplify the process.
  • Gender, height, level of fitness and your weight are all used to establish your body fat.
  • Obviously, hydration levels can still be an issue here.
  • As stated above, try to limit those variables by keeping hydrated and weighing during the same time of the day.
  • Consistency is the key.

Accuracy: Equal to the pinch test

Starting Cost: $50 (varies based on scale)

Convenience: It takes a minute or less and usually at home.



This is by far the most accurate body fat measurement method available.

The test requires you to exhale the air from your lungs as you get dunked into a pool of water.

The method only has an error margin of 1 body fat percentage point. 

Accuracy: The very best

Starting Cost: $25 to $50

Convenience: Accessible at many hospitals and various gyms, although, it is exhausting and can last up to an hour.

All The Gritty Details: This test requires weighing yourself outside of the tank, then submerging yourself completely in the water and weighing again.

Since bone and muscle is denser in water, while fat is less dense, a person with more bone and muscle will weigh more in water than a person who has less bone and muscle, which means that the latter has a higher body density and a lower body fat percentage.

  • The expectation with this method is that the density of fat mass and fat-free mass are consistent.
  • However, this method may not be suitable for everyone. For example, because athletes are inclined to having a denser body mass than non-athletes, this may lead to a gross miscalculation of body fat percentage.
  • In this way, the body fat of those with osteoporosis may also be miscalculated. Currently, there has not been any specific equation found to deal with these divergent groups.
  • In attempting this method, it is necessary to consider the amount of air remaining in your lungs after exhaling, as the remaining lung volume can be measured, and is beneficial to do so to get the best accuracy.
  • Also, make sure the environment in which you're testing is completely still.


Despite this method being considered the best, many people find it to be difficult, while others are afraid of water, or cannot completely exhale. Clinical studies will often have the subjects take the test several times, and the average be used for the results.



You step into an egg-shaped chamber, sit for 20 seconds, and that's it.

The chamber measures air displacement within your body.

This measurement is converted to your relative body fat after your weight is factored in. 

Accuracy: Initial tests show that it's as good as immersion.

Starting Cost: $25 to $125

Convenience: Found at only a few dozen hospitals and doctor's offices, but it's quick and easy. This method is limited by its high cost and limited availability.

All The Gritty Details: Constructed on the same basic design as underwater weighing, the BOD POD uses sensors to determine how much air is shifted while an individual sits for 20 seconds in a capsule. It applies a calculation to decide body density, then predicted body fat.



A new technology that is both accurate and decisive, DEXA is established on a three-compartment model that breaks down the body into total body mineral, lean mass, and fat mass.

This procedure is based on the belief that bone mineral content is directly comparable to the amount of photon energy absorbed by the bone being examined.

DEXA utilizes a whole-body scanner that has two low dose x-rays at multiple sources that read bone and lean mass at the same time.

  • The sources are then mounted under a table with a detector overhead.
  • The scanner passes across a person's body where data is acquired at intervals of 0.5 cm.
  • A scan usually lasts between 10-20 minutes.
  • It is a safe and non-invasive test to the individual, although they must lie completely still throughout the scan.

This test is quickly becoming the new best thing because it accommodates a much larger degree of accuracy in only one measurement and has the capability to show exactly where fat is spread out inside the body.

It is very dependable, safe, and poses almost no burden to the individual.

Though this test is not as precise in testing the extremely obese, and the cost of equipment is high, DEXA is rapidly moving from the lab setting into clinical studies.



A fiber optic probe is attached to a digital interpreter that indirectly measures the tissue makeup (fat and water) at multiple locations on the body.

This method of testing is derived from studies that show optical densities are linearly applied to subcutaneous and total body fat.

The biceps are usually the location that is most often tested for estimating body fat using the NIR method.

The NIR light penetrates the tissues, bounces off the bone, and back to the detector.

The NIR data is then entered into an equation along with the person's height, weight, frame size, and level of exercise to predict their body fat percentage.

This method has caught on with the public because it is simple, fast, non-invasive, and cost efficient.

Despite all this, the amount of pressure directed on the fiber optic probe during testing may affect the accuracy of measurements of the optical densities, with skin color and hydration level being potential sources of error.

To this day, studies done with this method have had mixed results, with a high degree of error occurring with very lean and very obese individuals.

Many sources detail the importance of further research to confirm the effectiveness, accuracy and suitability of this method.



The MRI is an x-ray-based method in which a magnetic field stimulates water and fat molecules in the body, creating a measurable signal.

An individual lies completely still within the magnet as a computer scans the body.

High-quality images show the volume of fat and where it is dispersed throughout the body.

An MRI takes around half an hour and is very safe since it doesn't use any ionizing radiation, but it is limited in its use due to the high cost of the equipment and testing.



This method of test is established by lean tissue being able to conduct electricity better than fat.

An individual lies in a chamber that creates a very weak electromagnetic field.

The strength of the field relies upon the electrolytes that are found in the individual's body water.

In around 10 seconds, TOBEC produces 10 conductivity readings that evaluate lean body mass.

Although this method is very accurate, its use is limited due to its high cost.



Computed Tomography generates cross-sectional scans of the individual's body.

An x-ray tube relays a beam to a detector.

As the beam rotates around the individual, data is compiled, saved, and applied to complex algorithms to create images that establish the composition of their body mass.

CT is specifically useful in producing a ratio of intra-abdominal fat to extra-abdominal fat.

This method is non-invasive, but the potential is limited by exposure to radiation, and its high cost.


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