# What Is the Average IQ in Japan? The 106 Claim, Examined

> The average IQ of Japanese people is 100 by definition on intelligence tests normed in Japan. The claim that Japan's average is 106 and among the highest in the world comes from the estimate of 106.48 in the national IQ list compiled by Lynn and Becker in 2019. That value was calculated from four studies of children and from international school assessment results, and the authors themselves caution that it should not be used as an exact IQ for individual countries or to rank countries with similar scores. In PISA 2025, meanwhile, Japanese 15-year-olds ranked first among OECD members in science, mathematics, and reading, and Japanese adults ranked second in literacy and numeracy in PIAAC. School assessments are not IQ tests, but several surveys consistently show that cognitive skills in Japan are high by international standards.

- URL: https://brainrank.jp/en/blog/japanese-average-iq
- Published: 2026-10-05
- Publisher: BrainRank Editorial Team (https://brainrank.jp)
- Tags: IQ basics, Psychology

The average IQ of Japanese people is 100 by definition, as long as it is measured with an intelligence test normed in Japan. The claim that Japan's average IQ is 106 and among the highest in the world comes from research that estimates national IQs; it is not a value confirmed by giving every country the same test. This article looks at where the 106 figure comes from and its limits, where Japan stands in representative international surveys (PISA and PIAAC), and how IQ has changed over time.

## Japan's average IQ is 100 by definition

IQ expresses a person's position relative to others of the same age. A test is given to a sample chosen to match the country's population, the score distribution is examined, and conversion norms are built so that the mean is 100 and the standard deviation is 15. This procedure is called standardization. The Japanese edition of the WAIS-IV (published in 2018, for ages 16 years 0 months to 90 years 11 months) likewise scores people against their Japanese age group ([Nihon Bunka Kagakusha, WAIS-IV](https://www.nichibun.co.jp/seek/kensa/wais4.html)).

In other words, the Japanese average on a Japanese-normed test is 100 by construction. Saying that Japan's average IQ is 106 only has meaning when some other standard, mainly British norms in national IQ research, is set to 100. The relative nature of IQ is explained in [the average IQ and standard deviation](https://brainrank.jp/en/blog/iq-average) and [what IQ is](https://brainrank.jp/en/blog/what-is-iq).

## Where the claim that Japan's average IQ is 106 comes from

The figure of 106 comes from a list of national IQs compiled by Richard Lynn and David Becker in 2019, which gives Japan 106.48. It is the average of two components: 107.41 derived from intelligence test studies, and 105.55 obtained by converting results from international school assessments such as PISA and TIMSS onto an IQ scale ([Lynn & Becker, 2019, The Intelligence of Nations](https://viewoniq.org/)).

However, only four intelligence test studies lie behind that value, and all of them tested children (mean ages 5 to 10). They were published between 1987 and 2005, and the scores were adjusted with corrections for factors such as the year of testing. This is not the result of giving one test to a representative sample of Japanese adults.

The authors themselves write that the dataset is suited to examining broad cross-national patterns and should not be used as an index of the exact IQ of individual countries or to rank countries that score close to one another (same book). Headlines announcing Japan's world ranking use the data in a way its compilers advise against.

## The limits of national IQ data: representativeness and comparability

National IQ lists have been strongly criticized by researchers. The demographer Rebecca Sear points out that most of the underlying data come from small samples that do not represent their national populations, including samples of children only and data going back to the 1940s, and concludes that the datasets should not be used to draw inferences about global variation in intelligence ([Sear, 2022, PsyArXiv preprint](https://doi.org/10.31234/osf.io/26vfb)).

It has also been shown that the numbers move substantially when the data are gathered differently. When studies on the average IQ of sub-Saharan Africans were collected again systematically with explicit criteria, the value given as below 70 in the earlier list came out at about 82 ([Wicherts and colleagues, 2010, Intelligence](https://doi.org/10.1016/j.intell.2009.05.002)). National IQ is an estimate that can shift by more than 10 points depending on which studies are included. We cover this issue in [can national average IQs be trusted?](https://brainrank.jp/en/blog/iq-by-country) as well.

## Japan in school assessments: first among OECD members in PISA 2025

The OECD's assessments are surveys that give the same questions to nationally representative samples. In PISA 2025, which tested 15-year-olds (91 countries and economies, about 760,000 students), Japan's mean scores were 538 in science, 525 in mathematics, and 503 in reading. It was the first time since the survey began that Japan ranked first among OECD members in all three domains; among all participants it ranked fifth in science, fourth in reading, and fifth in mathematics ([MEXT and the National Institute for Educational Policy Research, Key Points of PISA 2025](https://www.nier.go.jp/05_kenkyu_seika/pisa/pdf/2025/01_point.pdf)).

| Domain | Japan (PISA 2025) | OECD average | Rank among OECD members | Previous (PISA 2022) |
| --- | --- | --- | --- | --- |
| Science | 538 | 482 | 1st | 547 |
| Mathematics | 525 | 463 | 1st | 536 |
| Reading | 503 | 461 | 1st | 516 |

Reading, however, fell 13 points from the previous round, and the share of low scorers rose in all three domains (same source). Ranking high is not the same as having no problems.

The same pattern appears among adults. In the second cycle of the OECD Survey of Adult Skills (PIAAC), which covers ages 16 to 65 (31 countries and economies, about 160,000 people), Japan scored 289 in literacy and 291 in numeracy, second among participants in both, and 276 in adaptive problem solving, level with Finland at the top ([MEXT and the National Institute for Educational Policy Research, Key Points of the PIAAC Second Cycle](https://www.nier.go.jp/04_kenkyu_annai/pdf/02_PIAAC_CY2_point2.pdf)).

These assessments are not IQ tests. They measure knowledge acquired through schooling and the ability to apply it, and they are strongly shaped by the education system. Even so, Japan's consistently high position in representative samples is firmer ground than national IQ estimates, as long as the claim is limited to saying that cognitive skills in Japan are high by international standards. The link between attainment and intelligence is covered in [IQ and academic performance](https://brainrank.jp/en/blog/iq-and-grades), and the debate over smartphones and attainment in [school phone bans](https://brainrank.jp/en/blog/school-phone-ban).

## How big a difference is IQ 106?

Even if Japan's average were 106 against British norms, the difference would be 6 points, or 0.4 standard deviations. On a normal distribution with a mean of 100 and a standard deviation of 15, about 34.5% of people (roughly 1 in 3) score 106 or above, which as an individual score is within the average range.

Even when two national averages differ by 6 points, the two distributions overlap for the most part. You cannot infer an individual's ability from a national average. By the same calculation, IQ 110 is about the top 25% ([the share of people with IQ 110](https://brainrank.jp/en/blog/iq-110-percentage)) and IQ 130 about the top 2.3%. You can check where each score sits in the [IQ reference chart](https://brainrank.jp/en/iq).

## Has Japanese IQ risen? The Flynn effect

Average scores on intelligence tests rose in many countries throughout the 20th century, a phenomenon called the Flynn effect. Flynn's 1987 paper compiled data from 14 nations and reported that in Japan the full-scale IQ of children aged 6 to 15 rose by about 20 points in the 24 years from 1951 to 1975 ([Flynn, 1987, Psychological Bulletin](https://doi.org/10.1037/0033-2909.101.2.171)). Flynn himself, however, rated these data as tentative, since they rest on a single comparison.

Tests are restandardized every few decades, which resets the mean to 100. For that reason the IQs of Japanese people in the past and today, or of people in different countries, cannot be compared from the numbers alone. See [the Flynn effect](https://brainrank.jp/en/blog/flynn-effect) for details. Average differences between men and women are covered in [IQ gender differences](https://brainrank.jp/en/blog/iq-gender-differences).

## Your own position matters more than the national average

National average IQs depend heavily on how they are estimated. What can be said with confidence is only that the mean is 100 on tests normed in Japan, and that Japan performs at a high level in representative school and adult skills assessments. If you want to know roughly where you yourself stand, [BrainRank's free IQ test](https://brainrank.jp/en/start) scores 20 questions (about 10 minutes) across four domains, spatial reasoning, pattern recognition, logical reasoning, and classification, using item response theory (IRT), and returns an estimated IQ on a mean-100, SD-15 scale. Taking it is free with no signup; viewing the results, including the estimated IQ, is a one-time payment of ¥300 (tax included), with no subscription or auto-renewal (the result can be reopened for 24 hours after it is first shown, and saved as an image or PDF during that window). Results are estimates for entertainment and self-understanding, not a medical or diagnostic assessment.

## Frequently asked questions

### Where does Japan rank in the world for average IQ?

No reliable ranking can be given. The often-quoted figure of 106.48, said to be among the world's highest, is an estimate assembled from studies whose samples and dates differ by country, and its authors state that it should not be used to rank countries with similar scores. Representative international surveys exist for school attainment: in PISA 2025 Japan ranked first among OECD members in science, mathematics, and reading. School assessments do not measure IQ itself, however.

### What percentile is an IQ of 106?

On a normal distribution with a mean of 100 and a standard deviation of 15, an IQ of 106 or above is about the top 34.5%, roughly 1 in 3 people. It is 6 points, or 0.4 standard deviations, above the mean, which as an individual score falls within the average range. By the same calculation IQ 110 is about the top 25% and IQ 120 about the top 9%. A national average a few points higher does not mean each person in that country has a high IQ.

### Has the IQ of Japanese people risen over time?

There are data suggesting it has. Flynn's 1987 paper reported that the full-scale IQ of Japanese children aged 6 to 15 rose by about 20 points in the 24 years from 1951 to 1975. Flynn himself rated these data as tentative, and the figure rests on a single comparison. Because intelligence tests are periodically restandardized to reset the mean to 100, the IQs of people from different generations cannot be compared from the numbers alone.

## Sources

- [Nihon Bunka Kagakusha, WAIS-IV](https://www.nichibun.co.jp/seek/kensa/wais4.html)
- [Lynn & Becker, 2019, The Intelligence of Nations](https://viewoniq.org/)
- [Sear, 2022, PsyArXiv preprint](https://doi.org/10.31234/osf.io/26vfb)
- [Wicherts and colleagues, 2010, Intelligence](https://doi.org/10.1016/j.intell.2009.05.002)
- [MEXT and the National Institute for Educational Policy Research, Key Points of PISA 2025](https://www.nier.go.jp/05_kenkyu_seika/pisa/pdf/2025/01_point.pdf)
- [MEXT and the National Institute for Educational Policy Research, Key Points of the PIAAC Second Cycle](https://www.nier.go.jp/04_kenkyu_annai/pdf/02_PIAAC_CY2_point2.pdf)
- [Flynn, 1987, Psychological Bulletin](https://doi.org/10.1037/0033-2909.101.2.171)

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Statistics and percentages are calculated from a normal distribution model with a mean of 100 and a standard deviation of 15. The tests on this site provide estimates for entertainment and self-understanding; they are not medical or clinical assessments, nor official intelligence tests.
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