# IQ Gender Differences: Same Average, Different Spread and Skills

> There is almost no gender difference in average IQ. The major intelligence tests are built so that total scores do not differ by gender, and a Scottish survey of more than 80,000 11-year-olds likewise found no significant difference in the averages. Where differences do appear is in variability and in specific abilities. In the same survey, boys' scores were more spread out, and boys outnumbered girls in both the highest and the lowest score ranges. On specific abilities, men tend to score higher on mental rotation (d=0.56) and women on verbal fluency and processing speed. A US study of more than 7 million students, on the other hand, found a gender difference in math of nearly zero (d=0.0065). Of 124 effect sizes from research on psychological gender differences, 78% were small or close to zero, and the conclusion of the research is that men and women are more alike than different.

- URL: https://brainrank.jp/en/blog/iq-gender-differences
- Published: 2026-09-28
- Publisher: BrainRank Editorial Team (https://brainrank.jp)
- Tags: IQ basics, Psychology

Are there gender differences in IQ? The research answer is "almost none in the average. What differs is how widely scores are spread and the pattern of strengths and weaknesses on specific abilities." Even though average general intelligence is the same, consistent differences have been reported on some abilities, such as spatial ability and verbal fluency. Drawing on large-scale surveys and meta-analyses, this article lays out where the differences are and where they are not.

## The bottom line: almost no gender difference in average general intelligence

A report by a task force of the American Psychological Association (APA) states that most standard intelligence tests are constructed so that total scores show no gender difference, and that where differences are reported they are small and inconsistent in direction ([Neisser and colleagues, 1996, American Psychologist](https://differentialclub.wdfiles.com/local--files/definitions-structure-and-measurement/Intelligence-Knowns-and-unknowns.pdf)).

Evidence that does not depend on how a test was designed comes from a population-wide survey in Scotland. In 1932, more than 80,000 children who were 11 years old that year were given the same intelligence test, and there was no significant difference in average IQ between boys and girls ([Deary and colleagues, 2003, Intelligence](https://doi.org/10.1016/S0160-2896%2803%2900053-9)). On the WISC, the test for children, no gender difference has been found in full-scale IQ either ([Esposito & Giofrè, 2025, Journal of Intelligence](https://pmc.ncbi.nlm.nih.gov/articles/PMC11856952/)).

## What differs is variability: more males at both the top and the bottom

In the Scottish survey, although the averages were the same, the spread of scores (the standard deviation) differed significantly between boys and girls: boys' scores were more variable, and boys outnumbered girls in **both** the highest and the lowest score ranges (Deary and colleagues, 2003).

In a group with greater variability, a larger share of people fall at both ends of the distribution even when the average is the same. On US math tests too, boys' scores were 1.11 to 1.21 times as variable as girls'. However, among 11th graders in Minnesota, the ratio of boys to girls in the top 1% was 2.06 among White students but reversed, at 0.91, among Asian American students, so the ratio changes from group to group ([Hyde and colleagues, 2008, Science](https://dericbownds.net/uploaded_images/hyde.pdf)). You can check the IQ distribution and the share of people at each end in [what percentage has an IQ of 140](https://brainrank.jp/en/blog/iq-140-percentage) and [what is borderline intellectual functioning?](https://brainrank.jp/en/blog/borderline-intelligence).

## Gender differences by ability: spatial for men, verbal fluency and processing speed for women

Even where total scores show no difference, consistent differences have been reported on specific abilities. The size of a difference is expressed as the effect size d (as a rule of thumb, 0.2 is small, 0.5 medium, and 0.8 large).

| Ability | Who tends to score higher | Size of the difference | Source |
| --- | --- | --- | --- |
| Mental rotation (turning figures in your head) | Men | d=0.56 (medium) | Voyer et al. 1995 |
| Spatial perception | Men | d=0.44 | Voyer et al. 1995 |
| Spatial visualization | Men | d=0.19 (small) | Voyer et al. 1995 |
| Verbal fluency and synonym generation | Women | d=0.5 to 1.2 | Neisser et al. 1996 |
| Processing speed (e.g., matching digits and letters) | Women | Reported in many studies | Roivainen 2011 |
| Math (elementary through high school) | No difference | d=0.0065 | Hyde et al. 2008 |

The figures for spatial abilities come from Hyde's summary table of meta-analyses of gender differences ([Hyde, 2005, American Psychologist](https://www.apa.org/pubs/journals/releases/amp-606581.pdf)). On processing speed, one review found that women are faster on tasks that involve quickly matching digits and letters, while men are faster on reaction time and finger tapping ([Roivainen, 2011](https://eric.ed.gov/?id=EJ917070)). WISC studies likewise report that girls tend to score higher on processing speed and short-term memory, and boys on visual processing and crystallized intelligence (Esposito & Giofrè, 2025).

Because these differences in strengths cancel each other out, overall IQ shows almost no difference. Spatial ability is also known to improve with practice, which is covered in [how to train spatial reasoning](https://brainrank.jp/en/blog/spatial-reasoning-training).

## The gender difference in math is close to zero

The image that "men are good at math" is deep-rooted, but a study that analyzed state test results for more than 7 million US students in grades 2 through 11 found a gender difference in math of d=0.0065, effectively zero (Hyde and colleagues, 2008).

International comparisons also show that the size of the difference varies by country. In data from PISA 2003 (40 countries, 276,165 students), girls scored 10.5 points lower than boys in math on average, but the gap ranged from 22.6 points in Turkey to girls scoring 14.5 points higher in Iceland; the math gap was smaller in countries with greater gender equality, and it had nearly disappeared in Norway and Sweden ([Guiso and colleagues, 2008, Science](https://www.kellogg.northwestern.edu/faculty/sapienza/htm/science.pdf)). In reading, girls scored well above boys in many countries.

## Japan in PISA 2022: boys higher in math, girls higher in reading

In data on 15-year-olds in Japan, the OECD's PISA 2022 found that boys scored 9 points higher than girls in mathematics and girls scored 17 points higher than boys in reading ([OECD, 2023](https://www.oecd.org/content/dam/oecd/en/publications/reports/2023/11/pisa-2022-results-volume-i-and-ii-country-notes_2fca04b9/japan_aa63210c/f7d7daad-en.pdf)).

- Top performers in mathematics (Level 5 or 6): 27% of boys, 19% of girls
- Top performers in reading: 13% of girls, 12% of boys
- Low performers in reading: 17% of boys, 11% of girls

Japan's mean scores were 536 in mathematics, 516 in reading, and 547 in science, all high by international standards. Achievement tests are not the same thing as IQ, but the pattern of more boys among the top performers in math and more boys among the low performers in reading also fits the tendency seen earlier for boys' scores to be more variable.

## Men and women are more alike than different

The psychologist Hyde sorted 124 classifiable effect sizes from 46 meta-analyses and showed that 30% were close to zero (d≤0.10) and 48% were small (0.11 to 0.35), so that **78%** in total were small or close to zero (Hyde, 2005). This view is known as the "gender similarities hypothesis."

Even with a relatively large difference such as the d=0.56 for mental rotation, the distributions for men and women overlap heavily: calculated from normal distributions, about 29% of women score above the male average. You cannot infer an individual's ability from their gender, and it is far more useful to look at each person's own strengths and weaknesses. The different facets of intelligence are explained in [what cognitive abilities are](https://brainrank.jp/en/blog/cognitive-abilities) and [multiple intelligences theory](https://brainrank.jp/en/blog/multiple-intelligences).

## How to check your own strengths

Your own ability profile tells you far more than average differences between the genders do. [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 along with your strengths and weaknesses by domain. 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

### Who has the higher IQ, men or women?

On average, neither. Major intelligence tests such as the WAIS and the WISC are designed so that total scores do not differ by gender, and in a population-wide survey of more than 80,000 11-year-olds, average IQ was almost the same for boys and girls. An analysis pooling WISC studies likewise found no gender difference in full-scale IQ. The differences show up not in the average but in how widely scores are spread and in strengths and weaknesses on specific abilities.

### Why are there more men among people with very high or very low IQs?

The likely explanation is that men's scores are more variable. Even with the same average, greater variability puts a larger share of people at both ends of the distribution (very high and very low). In the Scottish survey, boys outnumbered girls in both the highest and the lowest score ranges, and on US math tests boys' scores were 1.11 to 1.21 times as variable as girls'. The ratio of males to females in the top 1% differs from group to group, however, and social factors have also been pointed to as an influence.

### Are there gender differences in academic achievement among children in Japan?

The direction flips depending on the subject. In the OECD's PISA 2022, boys in Japan scored 9 points higher than girls in mathematics, and girls scored 17 points higher than boys in reading. Top performers in mathematics (Level 5 or above) made up 27% of boys and 19% of girls, and low performers in reading made up 17% of boys and 11% of girls. In international comparisons, there is also research finding that the gender gap in math is smaller in countries with greater gender equality, so social factors are thought to be involved in the differences as well.

## Sources

- [Neisser and colleagues, 1996, American Psychologist](https://differentialclub.wdfiles.com/local--files/definitions-structure-and-measurement/Intelligence-Knowns-and-unknowns.pdf)
- [Deary and colleagues, 2003, Intelligence](https://doi.org/10.1016/S0160-2896%2803%2900053-9)
- [Esposito & Giofrè, 2025, Journal of Intelligence](https://pmc.ncbi.nlm.nih.gov/articles/PMC11856952/)
- [Hyde and colleagues, 2008, Science](https://dericbownds.net/uploaded_images/hyde.pdf)
- [Hyde, 2005, American Psychologist](https://www.apa.org/pubs/journals/releases/amp-606581.pdf)
- [Roivainen, 2011](https://eric.ed.gov/?id=EJ917070)
- [Guiso and colleagues, 2008, Science](https://www.kellogg.northwestern.edu/faculty/sapienza/htm/science.pdf)
- [OECD, 2023](https://www.oecd.org/content/dam/oecd/en/publications/reports/2023/11/pisa-2022-results-volume-i-and-ii-country-notes_2fca04b9/japan_aa63210c/f7d7daad-en.pdf)

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