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What is the IQ Scale? IQ Scale Explained

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The IQ scale is the metric that measures the results of an intelligence test, specifically an intelligence quotient test. 


The scale allows for a reliable reading of the test taker’s intelligence because it is the same regardless of a person’s age. IQ tests are tailored to the age of the test taker, so the IQ scale reflects the intelligence level based on the specific test.


Curious about where you rank on the IQ Scale? Find out with this quick IQ test >>>

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Though some tests differ in length, format, or types of questions asked, the IQ scale is generally the same. The scale keeps results standard across all tests regardless of the format and content. This way, a Wechsler Adult Intelligence Scale and an IQ test for kids still reflect the same score table relative to the person taking the test. 

Table of Contents

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IQ tests are tailored to the age of the test taker, so the IQ scale reflects the intelligence level based on the specific test.

What is the IQ Scale?

The IQ Scale is the metric used to determine an intelligence quotient score after an IQ test. The scale goes from 40 to 160. The score that denotes average intelligence is 100, but most people fall between 85 and 115. The top 2% of the population scores 145 and above. They are considered geniuses.

It was originally created as a way to determine a person’s mental age versus their biological age. The scale was not as standardized as it is today because the average intelligence score was someone’s age times 100. 


The following are the general categories of intelligence. 


  • Above 130: Very Gifted
  • 121-130: Gifted 
  • 111-120: Above Average Intelligence
  • 90-110: Average Intelligence
  • 80-89: Below Average Intelligence 
  • 70-79: Cognitively Impaired

Related: What is a Normal IQ?

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Who Should Use the IQ Scale?

Anyone taking an IQ test should use the IQ scale to determine the test results. Many online tests will calculate the results using the IQ scale, so you do not have to try to calculate it yourself.

If the IQ test is given in a medical or academic setting by a certified specialist, they will know how to read the IQ scale for accurate results.

Why is the IQ scale Important?

The IQ scale is important to the test because it is how you discover the results post-testing. The importance of using an IQ test to determine intelligence has its pros and cons. We will cover that in a later section. 


The importance of IQ tests is debatable. Online versions are fun to take, but you should take the results with a grain of salt because they are not always the most accurate displays of a person’s intelligence. 

What is a Good IQ Score for Your Age?

A complete breakdown of how to calculate IQ scores will be explained later in this article. However, a good IQ score for your age would be 100 or above. 

Does IQ Increase with Age? 

For the most part, IQ does not increase with age. As mentioned, the scale reflects results based on the test taker’s age. So, as long as the person is growing chronologically and mentally in the same upward trend, their IQ should be the same for their entire life. 

What Causes IQ to Drop? 

A decrease in IQ is usually due to some form of mental trauma, in most cases physically, but in other cases mentally. There is some evidence to suggest environmental factors like an increase in online time, changes in nutrition, the manner of education, and less reading in society overall. 

Is Your IQ Genetic or Learned? 

Intelligence seems to be largely genetic, though some environmental factors can affect this. Studies on sets of twins have shown that about 60% of the factors determining a person’s intelligence and aptitude in learning environments come from genetics. 

When Does Your IQ Peak? 

As mentioned, most people should have a similar IQ level throughout their lifetime. However, it is possible that children and young teens can grow their IQ as they continue to learn in educational systems and develop biologically. When you become an adult, your IQ tends to peak at about 20 years old. 


Studies show that there is a fluctuation in the teenage years of both verbal and non-verbal IQ scores, and the change correlates with changes in brain structure. However, these scores tend to level off as people turn 20 and enter adulthood.


Related: 50 People With the Highest IQ in the World

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Things to Note About the IQ Scale

Though intelligence tests are helpful tools in understanding where to place children in school or how well a teenager is maturing intellectually, they are not a definitive metric showing how smart someone is. The test does not allow for the assessment of creative abilities, emotional intelligence, artistic talents, or social skills and competence. 


With these limitations in mind, an important thing to note about the IQ scale is that it should be used as a guide to discovering intelligence levels, but not a definitive answer to the question of someone’s intelligence level.


The IQ scale is also a guideline of sorts. Although these categories of intelligence and their descriptions based on the IQ scale are generally accurate, they are not an end-all type of metric. 


If you need help deciphering your score on an IQ scale, talk with a certified professional to help you figure out what they mean. You can also have the test administered by a certified professional to be sure the test-taking environment is optimal for success. 

How to Calculate IQ Score Using IQ Scale

In short, the best way to calculate an IQ score using an IQ scale is to use the formula IQ = (intelligence age / chronological age) x 100. 


For instance, if someone is 15 years old chronologically and their test shows they are 15 in terms of intelligence, their score would be 100, as in 15 / 15 = 1, and 1 x 100 equals 100. 


If someone has a higher IQ the formula might look like this. If they are 15 years old, but they are a 17-year-old intellectually, the formula would be 17 / 15 = 1.13 repeating, which would roughly be 1.133 x 100 = 113 rounded down. 


Conversely, if they were lower on the IQ scale, the formula might look like 13 / 15 = 0.86 repeating, which would then be 0.866 x 100 = 87 rounded up. 


The formula is straightforward, but as you can see, even a one or two-year age difference in intelligence and chronological age can lend itself to a lower score than you might anticipate. These reasons are why you must visit a licensed professional for score interpretation, especially after an online test.


Related: What is Wechsler Adult Intelligence Scale?

Main Takeaways 

IQ tests are helpful tools in determining intelligence. However, they are not a complete indicator of the overall intelligence of a person. They do not take into account other types of intelligence or other types of intellectual abilities, such as creativity and artistic level. 


Take an IQ test if you are interested in learning more about your IQ level! There are plenty of options for free, online tests as well as tests that are administered by licensed psychological professionals. 

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