How common is an IQ of 133

Meaning of an IQ score / an IQ scale

What does an IQ score mean? What is the average IQ? After taking an IQ test, you may need some help interpreting your IQ score to understand what your IQ score is actually telling you. Is Your IQ Average? Do you have an ingenious IQ score? The following table shows an IQ level diagram that provides a clear overview of the one proposed by Resing and Blok (2002)1 derived IQ value ranges. The table distinguishes different categories based on the level of your IQ score, which means that you will get some understanding of your capacities.

IQPercentage of the population with this IQinterpretation
> 1302.1Gifted
111-12015.7Above average intelligent
90-11051.6Average intelligent
80-8915.7Intelligent below average
70-796.4Mentally retarded

What does my IQ score mean?

It is not always easy to understand what IQ test results mean. Most professional tests, such as the cross-cultural intelligence test or the classic intelligence test, not only give you a specific IQ score, but also an IQ range. This area shows you that your score can vary within this IQ scale: due to measurement errors and because the circumstances under which you take a test can have an influence. The average IQ score is always 100, and your personal score tells you your IQ ranking in comparison. The IQ scores are based on comparisons with other test subjects: the norm group. Since 100 is the average score, your score tells you how high your IQ score is compared to other people.

There is no such thing as a “normal IQ range”, although categories such as average intelligence can be distinguished (see table above). Most IQ classifications tend to pay attention to distinction when naming groups. So if you're trying to figure out what a brilliant IQ level is, “very gifted” might be the phrase you're looking for.

The normal distribution

Although the IQ score is widely known as a psychological statistic, its relation to other statistical measures is lesser known. The best way to explain these measures and their relations is using the normal distribution, also know as the Bell Curve.

Although the IQ score is commonly known as a psychological statistic, its relationship to other statistical measures is less known. The best way to explain these statistical measures and their relationships is through the normal distribution, also known as the bell curve. The following table shows a visual representation of a normal distribution. Think of the horizontal axis as all of the different scores you could get, from lowest to highest. The vertical axis represents the number of people who will receive that specific score.

An IQ test score is calculated based on a norm group with an average of 100 and a standard deviation of 15. The standard deviation is a measure of the spread, in this case the IQ values. A standard deviation of 15 means that 68% of the norm group are between 85 (100 - 15) and 115 (100 + 15). In other words, 68% of the norm group have a score within one standard deviation of the mean (100).

In addition, 95% of the norm group have an IQ score within two standard deviations from the mean. 95% of the norm group have a value between 70 (100 - 30) and 130 (100 + 30). This means that a value of over 130 is only achieved in 2.5% of the cases. For example, the Netherlands has 16 million inhabitants. By chance, only 25 of these residents would have an IQ of 170. There would only be one person with an IQ of 180. Only 4 in 1000 would get at least 140 points on an IQ test. Many online tests give you 130 or more points relatively easily. These tests often have a different purpose, such as gathering information for marketing purposes. The classic IQ test and the cross-cultural intelligence test require a small fee, but give you a reliable and accurate IQ value.

Recommended books on IQ and intelligence

  • What Is Intelligence ?: Beyond the Flynn Effect: Professor James Flynn is one of the most creative and influential psychologists in the field of intelligence. The "Flynn Effect" refers to the massive increase in IQ test scores over the course of the twentieth century. The term was coined to recognize Professor Flynn's central role in measuring and analyzing this increase. Author: James R. Flynn
  • The Curse of the High IQ: "Curse of the High IQ" is the first book specially written for unusually intelligent people. It identifies and addresses a litany of problems intelligent people face, analyzes them, and provides solutions. Author: Aaron Clarey

Find out more about IQ scores and differences, or take a free, short IQ test.

1Resing, W.C.M., & Blok, J.B. (2002). The classification of intelligence scores. Proposal for an unambiguous system. The psychologist, 37, 244-249.