The average IQ is 100, by design, and most people score between 85 and 115. This guide explains what that number really means, how the scale is built, how the average shifts by age, country, and education, and how to read your own score against it.
1 What Is the Average IQ? The Short Answer
Updated June 26, 2026 by Structural.The average IQ is 100. That is true on every major modern intelligence test, and it is true in every age group and almost every developed country, because the score is built that way rather than discovered. An IQ of 100 is the exact middle of the scale, and the great majority of people, roughly two thirds, score between 85 and 115.
The reason 100 is always the average is that IQ is a norm-referenced score. Test makers give the test to a large, representative sample, then set the mathematical center of that sample to 100 and spread the rest of the scores around it on a fixed scale. So when you ask what the average IQ is, you are really asking where the center of the reference population was placed, and the answer is 100 by construction. What varies between people is not the average but how far above or below it any individual falls.
100
Average IQ (by definition)
85-115
Normal range (about 68% of people)
15
Standard deviation on most tests
So a "normal" or "average" IQ is not a single number but a band. Scores from 90 to 109 are usually labeled average, with 85 to 115 counted as the broad normal range. Anything you read about average IQ by age, country, or job is a variation on this one idea, and this page is the hub that connects them. For the full scale at a glance, see the IQ Score Chart, and for what a single number actually tells you, see What IQ Scores Mean.
The most common misunderstanding is to treat 100 as a fixed quantity of intelligence, like a temperature or a weight. It is not. An IQ score is a relative measure: it tells you where you stand compared with other people of your age, not how much of some substance you possess. A score of 100 means you performed right at the median of the reference group, better than about half and worse than about half.
This is why the average is always 100. When a test is created or revised, psychometricians administer it to a carefully chosen standardization sample meant to represent the population, then convert raw answers into standard scores anchored so that the sample mean is 100 and the standard deviation is 15. The process is called norming, and it is what makes scores from different people comparable. If you want the detail of how that is done, see How IQ Scores Are Normed.
Two consequences follow that surprise people. First, the average cannot drift away from 100 within a properly normed test, because 100 is defined as the center. Second, raw ability can rise across a whole population over decades while the average IQ stays at 100, because the scale is periodically reset. Both facts come straight from the fact that IQ is a ranking expressed on a fixed scale, not an absolute count of mental horsepower. The standard deviation of 15 is the other half of that scale, and it controls how the rest of the scores spread out around the average.
3 The Bell Curve: How Scores Spread Around the Average
IQ scores follow a normal distribution, the familiar bell curve, which is symmetric around the average of 100. Because the standard deviation is 15 on most modern tests, the curve has a very predictable shape, and a few simple numbers describe almost the entire population:
About 68% score between 85 and 115, within one standard deviation of the average. This is the band most people mean by "normal."
About 95% score between 70 and 130, within two standard deviations. Almost everyone falls inside this wider range.
About 99.7% score between 55 and 145, within three standard deviations. Scores outside this are genuinely rare.
About 2.3% score above 130, the threshold often used for giftedness, and about 2.3% score below 70.
Because the curve is symmetric, the average of 100 is also the median and the most common single score. Half of all people score above 100 and half below, which is another way of saying 100 is the average. As you move toward the edges, scores become rapidly rarer: a 115 is fairly common, a 130 is roughly 1 in 44, and a 145 is around 1 in 1,000. You can see exactly how rarity climbs with the IQ Rarity Calculator, and how scores map to percentiles with the IQ Percentile Calculator.
This shape is why a small difference near the middle of the scale means little, while the same gap near the edges means a great deal. The distance from 100 to 110 covers a large slice of people, but the distance from 140 to 150 covers very few, because the curve is so thin out there. Keeping the bell curve in mind is the single best protection against misreading any average IQ figure, a point expanded in What IQ Scores Mean.
4 IQ Score Bands: What Counts as Low, Average, and High
Against the average of 100, scores are grouped into conventional classification bands. The exact labels vary slightly between test publishers, but the structure is consistent and tied directly to standard deviations from the average:
130 and above (gifted / very superior): top ~2.3%, two or more standard deviations above the average. See the Gifted IQ Range.
120 to 129 (superior): roughly the 91st to 97th percentile, clearly above average.
110 to 119 (high average): above the midpoint but within the normal range. See High Average IQ.
90 to 109 (average): the center of the distribution, where the largest number of people fall.
80 to 89 (low average): below the midpoint but still within the broad normal band.
70 to 79 (borderline): well below average, approaching the threshold used in clinical settings.
Below 70 (extremely low): the bottom ~2.3%, often relevant to formal diagnosis when paired with other criteria.
Notice that "average" is deliberately a range, not a single point, because no test is precise enough to treat one IQ point as meaningful. A real score always comes with a confidence interval, so a measured 100 is better understood as "somewhere close to the middle" than as an exact value. That margin of error is part of why a careful score report shows a band, a topic covered in Reliability and Validity. For the full labeled scale, the IQ Score Chart lays out every band and percentile.
5 Average IQ by Age
One of the most common follow-up questions is whether the average IQ changes with age. The short answer is no, by design: IQ scores are age-adjusted, so the average is 100 at every age, from childhood through old age. A 25 year old and a 70 year old who both score 100 are each average for their own age group, even though their raw cognitive performance may differ considerably.
Underneath that fixed average, raw abilities do change across the lifespan, and they do not all move together. Fluid reasoning and processing speed, the ability to solve novel problems quickly, tend to peak in the late teens to late twenties and decline gradually after that. Crystallized abilities, accumulated knowledge and vocabulary, tend to hold steady or even rise into the sixties. This split is the heart of the fluid versus crystallized distinction and the CHC model of cognitive abilities.
Because the scoring is age-normed, these raw changes are mostly hidden in the final IQ number, which is exactly the point: an IQ is meant to tell you your standing among peers, not your absolute ability compared with a twenty year old. For the detailed lookup of how raw performance and scores shift across the lifespan, see Average IQ by Age, which separates childhood development, the adult plateau, and later-life change.
6 Average IQ by Country
Searches for average IQ by country are enormous, and the topic needs care, because the published national figures are far less solid than they look. Various datasets assign each country an average IQ, often clustering developed nations near 100 and reporting lower figures elsewhere, but these numbers carry serious methodological problems and should be read as rough and contested rather than precise.
The reasons for caution are concrete. National estimates are frequently built from small, unrepresentative samples, different tests administered under different conditions, and studies conducted years or decades apart. They are heavily confounded by access to schooling, nutrition, health, familiarity with standardized testing, and language, all of which affect measured scores independently of any underlying difference. The Flynn effect, the long rise in raw scores over time, further distorts comparisons between studies from different eras.
The honest summary is that cross-country IQ comparisons mostly reflect differences in development, education, and measurement conditions rather than fixed properties of populations, and they are easy to misuse. Treated as a rough indicator of educational and developmental context, the data has some descriptive value; treated as a ranking of innate ability, it is not defensible. For the fuller breakdown and the caveats in detail, see Average IQ by Country.
7 Average IQ by Education and Profession
Average IQ also varies by how much education a person has completed and by occupation, and here the relationships are real and well studied, though still easy to over-read. On average, more years of schooling are associated with higher measured IQ, with correlations around .55, and certain professions show higher average estimated scores because they combine education filters, credentialing, and cognitively demanding work.
The relationship runs in both directions, which is important. Higher cognitive ability helps people stay in school and reach more demanding jobs, and schooling itself modestly raises measured IQ, by something like a few points per additional year. So the gap in average IQ between education levels reflects both selection and a genuine effect of education, not one alone. None of this means an individual's ceiling is fixed by their credentials, since the averages describe groups and hide enormous overlap between them.
8 Has the Average IQ Changed Over Time? The Flynn Effect
If the average is always set to 100, how can people say IQ has been rising? The answer is the Flynn effect, named for the researcher James Flynn, who documented that raw performance on IQ tests rose steadily across the twentieth century, by roughly three points per decade in many countries. People were genuinely answering more items correctly over time.
The average IQ still reads 100 in each era because the tests are periodically renormed. When a test is restandardized, the new, higher raw performance is reset to a mean of 100, which means a person scoring 100 today would likely have scored above 100 against the norms of fifty years ago. The rising tide is hidden precisely because the scale keeps being recalibrated to keep the average at 100. The likely drivers include better nutrition, more and better schooling, smaller families, and greater familiarity with abstract, test-like problems.
More recently, several developed countries have shown a slowdown or even a reversal of these gains, sometimes called a negative Flynn effect, though the evidence is still debated and the causes are unclear. The key takeaway for reading any average IQ figure is that it is always relative to a particular norming, so comparing scores across decades without accounting for renorming is a mistake. The full story is in The Flynn Effect Explained.
9 Average IQ by Sex and Other Groups
People often ask whether the average IQ differs between men and women. The mainstream finding is that average overall IQ is essentially the same for both, a result that is partly built in, because test makers typically balance items so that the full-scale average does not favor either group. Where differences appear, they are small and tend to sit at the level of specific abilities rather than overall scores, for example modest average advantages on some spatial or verbal subtests that partly offset each other.
A separate and more debated question concerns variability rather than averages, the hypothesis that one sex may be slightly more spread out across the range even when the means match. This remains contested and is sensitive to which tests and samples are used, so it should not be overstated. The responsible reading is that group averages are a poor guide to any individual, because the overlap between groups is far larger than any gap between them.
That overlap principle applies to every group comparison, by sex, age, education, or country. Averages can differ for many reasons, most of them environmental and developmental, while the range within each group dwarfs the difference between groups. This is why the only number that really describes you is your own score with its confidence interval, not the average of any category you belong to, a theme developed in Common Myths About IQ Tests Debunked.
10 Common Misconceptions About the Average IQ
Because the average IQ is so widely discussed, it attracts a lot of myths. A few are worth correcting directly:
"The average IQ proves how smart a group is." Averages reflect measurement conditions, education, and development at least as much as ability, and they hide huge individual variation.
"100 is a low or unimpressive score." A score of 100 is exactly average, ahead of half the population. It is the definition of typical, not a deficiency.
"The average IQ is rising, so people are getting smarter." Raw performance rose during the twentieth century, but the average score is reset to 100 by renorming, and recent trends are mixed.
"My IQ is a single exact number." Every real score has a margin of error, so it is best read as a band around a point, not a precise value.
"Online quizzes can tell me the average and my place in it." Only a properly normed test, scored against a real reference sample, can do that reliably, as discussed in Reliability and Validity.
Each of these traces back to the same root: forgetting that IQ is a relative score on a fixed scale, anchored to 100, rather than an absolute measurement. Hold on to that idea and most average-IQ confusion dissolves. For more on what a score does and does not capture, see What an IQ Test Measures.
11 How the Average Is Set: Norming and Standardization
The reason every reliable IQ figure traces back to 100 is the process of standardization. A test publisher recruits a standardization sample designed to mirror the population on age, sex, education, and region, administers the test under controlled conditions, and then statistically transforms the raw scores so the sample mean becomes 100 and the standard deviation becomes 15. Your score is then your standing relative to that sample.
This is also why test quality matters so much for any average you cite. A score is only as good as the sample it was normed on and the conditions under which it was given. A figure from a small, unrepresentative, or outdated sample can be off by a lot, which is exactly why casual internet quizzes and old cross-country datasets are unreliable. A properly built instrument reports its norms, its reliability, and its margin of error, as ACIS does in its Technical Manual and summarizes in Reliability and Validity.
It also explains why a real result is reported with a confidence interval rather than a bare number. Measurement always carries error, so a well-built test tells you not just your score but how tightly it is estimated, which is the difference between a meaningful comparison to the average and a guess. For how the broad score is assembled from many subtests, see Full Scale IQ and Cognitive Domains.
12 Where Do You Fall Against the Average?
Knowing that the average is 100 is only useful once you can place yourself against it. Your standing is best expressed as a percentile, the share of people you scored at or above. A score of 100 is the 50th percentile, 115 is about the 84th, 130 is about the 98th, and 85 is about the 16th. Percentiles are often more intuitive than raw IQ points because they translate the bell curve directly into "how many people."
The only way to know your real standing is to take a broad, properly normed assessment and read the result with its confidence interval, rather than guessing from an online quiz or comparing yourself to a national average. A real score places you on the same scale this whole page describes, with 100 as the anchor, and tells you your percentile against an adult reference frame. You can turn a score into a percentile with the IQ Percentile Calculator or read the bands on the IQ Percentile Chart.
It is worth stressing why the average alone cannot tell you your own standing. Knowing that the center of the scale is 100 says nothing about whether you sit at 92, 108, or 124, and the difference between those points maps to very different percentiles and very different everyday experiences of learning and problem solving. The average is the reference line, not your position on it. Two people can both describe themselves as ordinary while sitting fifteen points apart, which is a full standard deviation and a meaningful gap in relative standing. That is why a measured score, reported with its confidence interval and its percentile, is the only thing that answers the question most people are really asking when they look up the average IQ, which is not where the middle is but where they personally land against it.
"Average IQ" is not one question. Some readers want the meaning of the number, some want how it varies across groups, and some want to place their own score. This page is the overview, and the focused pages below handle the narrower lookups without forcing every topic onto one URL.
If the question is "what is the average IQ and what does it mean?", stay here. If it is "average IQ for a 30 year old" or "average IQ by country," use the focused pages. For how the average connects to real-world outcomes, continue to IQ and Success, and for the meaning of a good score specifically, see What Is a Good IQ?
14 Key Research References
For those interested in the primary sources behind the scale and its trends:
Flynn, J.R. (1987). Massive IQ gains in 14 nations: What IQ tests really measure. Psychological Bulletin, 101(2), 171-191.
Flynn, J.R. (2012). Are We Getting Smarter? Rising IQ in the Twenty-First Century. Cambridge University Press.
