What is the average IQ?

Short answer: The average IQ is 100, and it is 100 by definition. When a publisher builds a modern IQ test, it gives the test to a large norming sample and converts the scores to a scale with a mean of 100 and a standard deviation of 15 (APA task force report, 1996). The same report says about 95% of people score between 70 and 130. By the normal curve, about two-thirds score between 85 and 115.

What the average IQ means

Your IQ score compares you with a reference group. It is not a count of correct answers or a fixed amount of intelligence. Mensa International describes IQ as a standard score that shows how far above or below their peer group a person stands, with the peer group's average set at 100 (Mensa, "What is IQ?", page updated April 2024).

So a score of 100 means you landed in the middle of the people the test was normed on. That is why "what is the average IQ" has a fixed answer: the middle is always called 100, even if the raw performance behind it moves.

Why the average is always 100

IQ started as a real quotient. The psychologist William Stern coined the term in 1912. At that time a score was mental age divided by age, times 100, so a 10-year-old who performed like a typical 12-year-old scored 120 (Mensa, page updated April 2024). The psychologist Lewis Terman revised Binet's test as the Stanford-Binet and used the same idea. The Wikipedia article on IQ classification (last edited 1 October 2026) dates Terman's original Stanford-Binet classification to 1916.

The ratio worked poorly for adults, because mental age stops climbing while birthdays keep coming. David Wechsler replaced it with a deviation score. In his system, a person whose score equaled the mean of their age group got 100 (Mensa, page updated April 2024). The same Wikipedia article dates his Wechsler-Bellevue scale, the forerunner of the adult Wechsler test, to 1939. An APA task force report from 1996 (Neisser and colleagues) says the old quotient is no longer used, but the name IQ stayed.

Today the arithmetic runs the other way. A publisher tests a large sample, then converts raw scores onto a scale with a mean of 100 and a standard deviation of 15 (APA task force report, 1996). The 100 is a choice the test makers build in.

The normal range of IQ scores

Scores on this scale follow a bell curve. The bands work out like this, with the source of each figure:

• About 95% of people score between 70 and 130, two standard deviations either side of 100 (APA task force report, 1996).
• About two-thirds score between 85 and 115, one standard deviation either side. This figure is calculated from the normal curve.
• About 2.3% score above 130 and about 2.3% score below 70, also calculated from the normal curve.

Common scores sit at these percentiles, calculated from the normal curve with a mean of 100 and a standard deviation of 15:

• 85: about the 16th percentile
• 100: the 50th percentile
• 110: about the 75th percentile
• 115: about the 84th percentile
• 120: about the 91st percentile
• 130: about the 97.7th percentile

A worked example: say you score 115. That is one standard deviation above 100, so by the normal curve you scored higher than about 84% of the norming sample. Mensa's page (updated April 2024) puts the same score at 86%, so the two figures disagree. The normal curve gives about 84%.

What the score labels mean

Test publishers attach plain-language labels to score ranges. The Wikipedia article on IQ classification (last edited 1 October 2026) lists these labels as the ones used with the WAIS-IV, the fourth edition of the Wechsler Adult Intelligence Scale:

• 130 and above: Very Superior
• 120 to 129: Superior
• 110 to 119: High Average
• 90 to 109: Average
• 80 to 89: Low Average
• 70 to 79: Borderline
• 69 and below: Extremely Low

The same article says the WISC-V, the children's Wechsler scale, keeps the same ranges but renames three bands. Very Superior becomes Extremely High. Superior becomes Very High. Borderline becomes Very Low. So "average" on a Wechsler report covers 90 to 109, a band rather than the single number 100. A label describes a score. It is not a diagnosis, and a psychologist with a full clinical assessment can tell you what a score means for you.

Is the average IQ the same at every age?

Yes, by design. Wechsler-style tests compare you with people your own age. The WAIS-5, published by Pearson in 2024, covers ages 16 to 90, and its standard scores "are derived using age-based norms" (Pearson Q-global help, read October 2026).

So an average young adult and an average 70-year-old both score 100, each against their own age group, because the WAIS-5's age norms run from 16 to 90 (Pearson Q-global help, read October 2026). On an age-normed test, the average for each age group is 100.

Is the average IQ going up? The Flynn effect

Scores on IQ tests rose through most of the 20th century. The APA task force report (1996) puts the average gain at about three IQ points per decade. A 2014 meta-analysis of 285 studies by Trahan and colleagues (Psychological Bulletin) found 2.31 points per decade overall and 2.93 points per decade on modern Wechsler and Stanford-Binet tests. This rise is called the Flynn effect.

The rise is part of the reason tests get re-normed. The APA task force report (1996) says most tests are restandardized from time to time, in part to keep up with these gains. When that happens, the new sample's mean is typically set to 100 again, so the gain more or less disappears from view (APA task force report, 1996). The same report estimates that people who score 100 on a new version would average about 106 on a version normed 20 years earlier. An old test can therefore flatter you. Pearson's product page for the WAIS-5 lists updated norms among its changes (read October 2026).

Whether the rise continues is less clear, and the studies point different ways. Trahan and colleagues (2014) reported that their modern-test gains were not consistent with the hypothesis that the Flynn effect is diminishing. A 2015 meta-analysis in the journal Perspectives on Psychological Science, by Pietschnig and Voracek, covering almost 4 million participants tested between 1909 and 2013, found that the gains have shrunk in more recent decades. A 2023 study in the journal Intelligence, by Dworak, Revelle and Condon, used online data from 394,378 US adults collected from 2006 to 2018. It found a pattern consistent with falling scores on matrix reasoning and some other item types, while scores on three-dimensional rotation rose. In Northwestern University's release on the study (20 March 2023), corresponding author Elizabeth Dworak said the lower scores do not mean mental ability is lower, and that people could be getting worse at taking tests, or at these kinds of tests. The release adds that the project is advertised as a personality survey, so takers may have been less engaged with the ability items.

Why your score is a range

No test measures you perfectly. The APA task force report (1996) notes that a person's intellectual performance will vary on different occasions, in different domains and by different criteria. Clinical reports reflect that: the WAIS-5 score report lets the psychologist show each score with a 90% or 95% confidence interval (Pearson Q-global help, read October 2026).

A confidence interval is the range your true score most likely sits in. Its width depends on how reliable the test is. Take a made-up test with a reliability of .90. By calculation, its standard error is about 4.7 points on this scale, which gives a 90% range of about plus or minus 7.8 points. Two tests, or two sittings of the same test, can give you different numbers that both fall inside that range.

How a clinical IQ test differs from an online test

A clinical test like the WAIS-5 is given one to one by a trained professional. Pearson describes it as an individually administered clinical instrument that takes about 45 minutes for the Full Scale IQ and 60 minutes for the primary index scores (Pearson product page, read October 2026). Pearson sells it only to buyers at qualification level C. In general, that means a doctorate in psychology, education or a related field with training in assessment, a relevant state license, or full membership of a professional body that requires that training (Pearson qualifications policy, read October 2026).

Mensa draws a similar line. American Mensa accepts a Full Scale IQ of 130 on the Wechsler editions it lists, the WAIS through the WAIS-IV and the WISC through the WISC-V, or a score in the top 2% on other approved tests. It does not accept unsupervised or internet-based tests as proof of eligibility (American Mensa, read October 2026).

An online test gives you an estimate, so read it as one. It cannot diagnose anything, and it does not replace an assessment by a psychologist.

What an IQ score does not tell you

The APA task force report (1996) is direct about the limits. Standardized tests do not sample all forms of intelligence, and the report names creativity, wisdom, practical sense and social sensitivity as examples. Scores predict school grades fairly well, with a correlation of about .50, but that accounts for only about 25% of the variation in grades. The report names persistence, interest in school and willingness to study as other factors. The same report notes that experts do not even agree on one definition: when two dozen prominent theorists were asked to define intelligence, they gave two dozen somewhat different definitions.

So a score near 100 tells you where you landed against a norming sample, on one kind of task, on one day. It does not measure your worth, and it does not settle questions about learning, attention or development. For those, talk to a school or clinical psychologist.

If you want to see where you land, WhatIQ's test has 24 timed picture puzzles, takes about 15 minutes, and gives a score on the standard scale (average 100, standard deviation 15) with the 90% range it most likely sits in (whatiq.com, read 7 October 2026). It is an estimate from one short online sitting, not a clinical assessment.

Frequently asked questions

What is the average IQ for adults?

1. Adult tests such as the WAIS-5 score each person against people of the same age, so the average adult in each age group scores 100 (Pearson Q-global help, read October 2026).

What is the average IQ in America?

By convention, IQ tests are scaled so that the mean of their norming sample is 100, with a standard deviation of 15 (APA task force report, 1996). So for an American taking a test normed on a US sample, the average is 100 by design.

What is the average IQ for a teenager?

The WAIS-5 starts at age 16 and scores each person against their own age group (Pearson Q-global help, read October 2026). So the average 16-year-old taking it scores 100.

Is an IQ of 110 good?

110 is above the middle. By the normal curve it is about the 75th percentile, and on the WAIS-IV labels it sits at the bottom of the High Average band, 110 to 119. Any single score has a range around it, so a 110 on one test may read a few points differently on another.

What is the average IQ for a 70-year-old?

100, against other people of the same age. The WAIS-5's norms run to age 90 (Pearson Q-global help, read October 2026), so an older adult is compared with people their own age, not with young adults.

What IQ do you need for Mensa?

A score in the top 2% on an approved, supervised test. American Mensa lists a Full Scale IQ of 130 on Wechsler editions through the WAIS-IV and WISC-V, and does not accept internet-based tests (American Mensa, read October 2026).