The average IQ score is 100. That isn't a coincidence or a survey result — it's how IQ tests are built. Every major test is standardized so that the mean score of the norming sample is exactly 100, with a standard deviation of 15 points. About 68% of people score between 85 and 115 — the range most people mean by a normal IQ — and roughly 95% score between 70 and 130.
Quick answer
Average IQ is 100 on standard IQ tests. In practice, IQ is a relative ranking system: 85 to 115 covers about 68% of people, 90 to 109 is the common average band, and percentiles explain your standing more clearly than labels.
Why the average IQ score is always 100
When a new IQ test is developed (or an old one revised), it is given to a large, representative sample of people — the norming sample. Raw results are then mapped onto a bell curve centered at 100. Your IQ score is therefore not a count of correct answers; it's a statement about where you stand relative to everyone else. A score of 115 means you scored one standard deviation above the mean — higher than about 84% of the population.
What counts as a normal IQ?
There is no official definition of a normal IQ, but two conventions are in common use, and they differ only in how wide a net they cast. The narrower one is the classification band 90 to 109, which psychologists label "average" and which contains 49.5% of people. The broader one is 85 to 115 — one standard deviation either side of the mean, containing 68.3%. Either way, a normal IQ is not a threshold you pass or fail; it is the thick middle of a curve, and the great majority of people are in it.
What that means for an individual score is worth stating plainly: average intelligence is the single most common result there is. Half of all people score below 100 and half score above it, by construction. A result of 97 or 103 is not a meaningfully different outcome from 100 — the difference is smaller than the measurement error of the test itself, which is why how accurate IQ tests are matters more than the last few points of any score.
How IQ scores are distributed across the population
| IQ range | Share of population | Description |
|---|---|---|
| 130 and above | 2.28% | Very superior / gifted |
| 120–129 | 6.85% | Superior |
| 110–119 | 16.13% | High average |
| 90–109 | 49.50% | Average |
| 80–89 | 16.13% | Low average |
| 70–79 | 6.85% | Borderline |
| Below 70 | 2.28% | Extremely low |
For a deeper breakdown, see our guides to every IQ range and IQ level and the IQ score chart, or convert any score to a population rank with the IQ percentile table.
Average IQ for adults
The average IQ for adults is 100, and it is 100 for every adult age group separately. Modern tests are age-normed: a 32-year-old is scored against a sample of other 32-year-olds, and a 68-year-old against other 68-year-olds, so the mean cannot drift with age even though the underlying abilities do. This is the single most common misreading of adult IQ data — people expect the average to fall in later life, and it does not, because the yardstick moves with the person being measured.
Why some sources say the average human IQ is 85, not 100
Search for this and you will find both numbers stated confidently on the same results page. They are not contradictory; they answer different questions.
100 is a property of the scale, not a finding about people. A test publisher administers a new test to a norming sample — usually a nationally representative sample of one country in one period — and maps the raw results so that sample's mean lands on 100. Say "the average IQ is 100" and you have said something true by construction about that test, that country and that year.
A quoted average human IQ of 85 or 88 is a different claim: an estimate of how the world's population would score if measured against one country's norms. Those figures come from compilations that pool many separate studies using different tests, different years and samples of very uneven quality and size, and the best-known of them have been widely criticised on exactly those grounds. Treat any single global figure as an estimate with wide uncertainty rather than a measurement.
The clearest demonstration that "the average" is a moving reference point rather than a fixed fact is the Flynn effect below. Raw performance rose by roughly three points a decade through the 20th century, so a person scoring exactly 100 today would have scored well above the mean of a norming sample drawn in the 1950s — on the order of 15 to 20 points above it, if that rate held steady across the whole span, which in some countries it has not. The number 100 stayed put only because the tests were re-normed underneath it.
What average IQ means in practice
What is the definition of average IQ?
Average IQ means the midpoint of a standardized IQ scale. On modern SD-15 scales, that midpoint is fixed at 100 by design, not estimated from a casual poll.
Is average IQ the same as "normal IQ"?
Not exactly. "Average" is usually the 90 to 109 classification band, while many people use "normal" for the broader 85 to 115 range. Both describe common ranges around the same center of 100.
Can you compare two people by a 2-point IQ difference?
Usually no. Small gaps are often within normal measurement error. Interpret results as ranges plus percentile, not as precise rankings by single-point differences.
Where can I compare a specific score quickly?
Use the IQ score chart for broad ranges and the IQ percentile table for point-by-point conversions.
Average IQ by age
Because scores are age-normed, the average is 100 at every age: a 25-year-old and a 70-year-old are each compared to their own age group. Underneath the norming, raw abilities do change — fluid reasoning (solving novel problems) typically peaks in the 20s and gradually declines, while crystallized knowledge (vocabulary, facts, skills) keeps growing into the 60s — the distinction explained in fluid and crystallized intelligence. We cover the age pattern in detail in average IQ by age.
Average IQ by country — read with caution
You'll find many tables online claiming national average IQs. The honest summary: measured averages differ between countries, but the differences track education access, childhood nutrition, health care and test familiarity — and many national estimates are built on small or unrepresentative samples. Country rankings make good clickbait and poor science.
The Flynn effect: averages have been rising
Raw performance on IQ tests rose steadily through the 20th century — about 3 points per decade — a phenomenon named the Flynn effect after researcher James Flynn. Better schooling, nutrition, smaller families and a more abstraction-heavy world are the leading explanations. Because tests are re-normed, the published average stays at 100 even as raw performance shifts; some wealthy countries now show a plateau or slight reversal.
Source and interpretation notes
This page summarizes mainstream psychometric conventions. For careful interpretation, prioritize test manuals and peer-reviewed sources over social-media score claims or unsourced ranking lists.
- Definitions and score bands here align with common SD-15 frameworks used by major IQ tests.
- Country-level comparisons are noisy and often sample-limited, so they should not be treated as fixed truths about populations.
- Online scores are estimates; for formal decisions, use professionally administered assessments.
What "average" means for you
A single number can't capture a mind. Two people with identical IQ 100 scores can have very different cognitive profiles — one strong in working memory, the other in visual-spatial reasoning. That's why a useful assessment reports how you think, not just a number: your percentile, your strengths across abilities, and where focused training will move the needle — which, honestly, is a few points rather than a transformation.
If you want a practical baseline to place your own result on the same scale, you can start with the IQ test and score report and then interpret the result using the IQ testing methodology guide. At the other end of the distribution from the average sits the Mensa qualifying score, which roughly 2% of people reach.