What Is Considered a Normal IQ?

Renee Booker

An intelligence quotient, or IQ, is a numerical value assigned to an individual based on his or her performance on one or more standardized tests which are designed to determine or assess the person's inherent or genetic intelligence. The range for an IQ starts at zero and, in theory, has no upper limit, although the highest IQ scores ever recorded are around 200. Statistics show that approximately 95% of the population have IQ scores between 70 and 130, making a "normal IQ" 100.

A genius might score 30 to 40 points more on an IQ test than someone with a normal IQ.
A genius might score 30 to 40 points more on an IQ test than someone with a normal IQ.

Although there are an infinite number of tests that claim to test a person's IQ, there are a few that are widely used and recognized. The Stanford-Binet and the Wechsler Adult Intelligence Scale and Intelligence Scale for Children are just a few reputable tests used to determine whether someone has a normal IQ. Studies indicate that, although test scores may vary somewhat from one test to the other, scores tend to stay relatively constant regardless of the test taken.

A gifted person might have an IQ that is 15 to 20 points higher than an average IQ.
A gifted person might have an IQ that is 15 to 20 points higher than an average IQ.

In terms of what is considered a normal IQ, scientists have determined that 95% of all test takers score within two standard deviations of the mean. For purposes of an IQ test, one standard deviation is 15 points. The median score is set at 100, which means that the vast majority of all test takers score within 30 points on either side of the median — or between 70 and 130. Although 100 is the median, most experts consider a "normal IQ" to be anything within one to two deviations of the median, or in the 70 to 130 range.

Mental retardation and IQ are linked because having a below-average intelligence quotient (IQ) is required for diagnosis.
Mental retardation and IQ are linked because having a below-average intelligence quotient (IQ) is required for diagnosis.

When a test taker's IQ surpasses the normal IQ range, he or she is usually considered to be "gifted" or to have a "genius" IQ. Opinions differ with regard to where "normal" leaves off and "gifted" and "genius" begin. The general consensus, however, puts tests takers who score above 115 to 120 in the "gifted" category and those who score above 130 to 140 in the "genius" category.

The most accurate IQ tests are standardized tests that require proctoring.
The most accurate IQ tests are standardized tests that require proctoring.

Likewise, test takers who score below 70 are also considered to be outside the normal IQ range. An IQ score below 70 is considered to be a sign of mental retardation, or intellectual disability, by most experts. Many experts consider a score between 70 and 80 to be at the lower range, or borderline range, of intellectual functioning. Scores below 70 indicate mild to severe mental retardation, or the inability to function at a normal intellectual level.

Although there are an infinite number of tests that claim to test a person's IQ, there are a few that are widely used and recognized.
Although there are an infinite number of tests that claim to test a person's IQ, there are a few that are widely used and recognized.
Many experts consider a score between 70 and 80 to be at the borderline range of intellectual functioning.
Many experts consider a score between 70 and 80 to be at the borderline range of intellectual functioning.
IQ tests may be used to determine placement in a gifted class.
IQ tests may be used to determine placement in a gifted class.

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Discussion Comments

anon993203

I received an IQ score of 147. Is that good?

Phaedrus

Buster29, my school did things a little differently. We all took the IQ tests over a three day period. We were called into an office individually and a teacher would show us our scores, but obviously no one else's. We were urged not to make a big deal out of the numbers, but of course some students felt like telling everyone their IQ scores.

I was told at the time that a "normal" IQ score was between 90 and 110. Anything between 110 and 150 was considered gifted, and scores over 150 were considered genius. I scored a 120 myself, but I already suspected I was above average because of the advanced classes I was taking. I think those ranges have changed in recent years, or people are now taking different IQ tests. 140 on one test is considered genius, so it helps to know which test you took in order to understand the scores.

Buster29

When I took an IQ test back in middle school, they wouldn't let us know our scores. The idea was to keep those numbers hidden in our permanent records until we were old enough to request that information. A teacher told me that if we all knew our IQ scores, some students might get teased for having low numbers and others might start bragging about having high numbers. If there was a situation with a child's high or low IQ scores, the school administrators might have a discussion with that child's parents, but no one else.

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