How many IQ points can reading add?

A few points is a reasonable expectation. No study has put a point value on reading alone, but schooling, which includes reading, is estimated to raise IQ by about 1 to 5 points for each additional year (Ritchie and Tucker-Drob, 2018). In a study of identical twins, differences in reading ability also led to later differences in intelligence, but the effects were small to moderate. Reading will not raise your IQ by 10 or 20 points in a short time.

Do comics, e-books, or online articles count?

For building vocabulary and knowledge, the more text you read, the better your odds. The effects shown in research come mainly from reading books of prose, and the effect of reading volume shows up most clearly in vocabulary and reading comprehension. Note, though, that a meta-analysis found comprehension of informational text is somewhat lower on screens than on paper (Delgado and colleagues, 2018, g=−0.21), and the gap widens under time pressure. For text you want to understand thoroughly, reading on paper without rushing is the safe choice.

Is it worth starting to read as an adult?

Yes. The link between reading volume and vocabulary actually grows stronger with age: among college students, reading explained 34% of the variation in oral language skills such as vocabulary (Mol and Bus, 2011). A study that followed 294 older adults found that more cognitive activity in early and late life explained 14% of the variation in cognitive decline not accounted for by brain pathology (Wilson and colleagues, 2013). This is an observational study, however, so it cannot show that reading prevents decline.

Does Reading Raise IQ? What Twin Studies and Meta-Analyses Show

Published: 2026-09-28

In brief: Does reading raise IQ? The research answer is "a little, especially verbal ability." A study that followed 1,890 pairs of identical twins from age 7 to 16 found that the twin who learned to read well earlier went on to have higher nonverbal IQ as well as higher verbal IQ (Ritchie and colleagues, 2015). In a meta-analysis of 99 studies, the amount people read explained 13% of the variation in oral language skills such as vocabulary among elementary school children and 34% among college students. The gains, however, are on the order of a few points, the same range as the estimate that each year of education raises IQ by about 1 to 5 points. The well-known experiment claiming that reading a single piece of literary fiction boosts empathy did not replicate in a large follow-up study.

Does reading raise IQ? The research answer is "a little. It mainly builds verbal abilities such as vocabulary and knowledge, and there is evidence that it spills over into nonverbal reasoning too, but the gains are on the order of a few points." This article uses research data to lay out how large the effects are and where they stop, covering a long-term study of identical twins, a meta-analysis of reading volume, the link between education and IQ, cognitive function in old age, and the replication of the widely cited experiment claiming that fiction boosts empathy.

The bottom line: reading builds vocabulary and knowledge, with a small spillover into reasoning

Reading's effect shows up most clearly in crystallized intelligence (Gc), such as vocabulary and general knowledge. Because most IQ tests include vocabulary and knowledge items, verbal ability built through reading is also reflected in overall IQ. The effect on fluid intelligence (Gf), the ability to solve problems you have never seen, is smaller, and it does not rise much in a short time. The difference between Gf and Gc is explained in fluid vs. crystallized intelligence.

Ability	Strength of evidence	Key study
Vocabulary and oral language	Strong (consistent across many studies)	Mol & Bus 2011 (99 studies)
Verbal IQ	Moderate (near-causal evidence from a twin study)	Ritchie et al. 2015
Nonverbal IQ	Small to moderate (same study)	Ritchie et al. 2015
Empathy (theory of mind) from fiction	Weak (did not replicate in a large follow-up)	Panero et al. 2016
Cognitive function in old age	Observational studies only	Wilson et al. 2013

A study of 1,890 identical twin pairs: the twin who read earlier had higher IQ later

A correlation such as "kids who love books are smart" could simply mean that children who are already bright prefer books. A study by Ritchie and colleagues tackled this problem using data from TEDS, a UK twin study (Ritchie, Bates & Plomin, 2015, Child Development). It measured 1,890 pairs of identical twins at ages 7, 9, 10, 12, and 16 and compared the differences within each pair.

Identical twins share nearly all their genes and grow up in the same home, so a difference in reading ability that emerges between them can be attributed to factors other than genes or family environment. The analysis found that the twin with stronger reading ability at an earlier age went on to score higher at later ages on nonverbal intelligence as well as verbal intelligence. The study showed an effect running from reading ability to intelligence in a form closer to causation than a correlational study can. In the same study, however, the amount read (how much each twin read) did not show a similar effect. The takeaway is that what matters is developing reading ability, more than the number of books.

The link between reading volume and vocabulary grows stronger with age

The relationship between print exposure (how much text people encounter in books and elsewhere) and language ability has been summarized in a meta-analysis of 99 studies and 7,669 people (Mol & Bus, 2011, Psychological Bulletin). The share of the variation in oral language skills such as vocabulary explained by print exposure grew with age.

Preschool and kindergarten: 12%
Elementary school: 13%
Middle school: 19%
High school: 30%
College: 34%

Children who read well read more, and the more they read, the more words they learn, and through this cycle (the Matthew effect) the gap widens with age. For why books build vocabulary, a comparison by Cunningham & Stanovich (1998) is a clear example. The number of rare words per 1,000 words was 30.9 in children's books, 22.7 in prime-time adult TV shows, and 17.3 in conversation between college graduates. Even children's books contain more uncommon words than adult conversation.

Education adds about 1 to 5 IQ points per year, and reading is at its core

No study has isolated reading alone and measured how much it raises IQ, but the effect of schooling, which centers on reading, has been estimated. A meta-analysis combining 42 datasets and more than 600,000 people found that each additional year of education raises IQ by about 1 to 5 points, that the effect persists into adulthood, and that it appears across every cognitive ability measured (Ritchie & Tucker-Drob, 2018, Psychological Science). The estimates vary with study design: about 1.2 points in studies controlling for earlier IQ, about 2.1 points in studies using changes in compulsory schooling laws, and about 5.2 points in studies using school-entry age cutoffs.

Training reliably improves the trained task; the gains often carry to similar tasks (near transfer) but rarely to intelligence in general (far transfer).

Training that repeats a specific task, like brain-training games, is known to improve that task while transferring poorly to others (how to raise your IQ, how to train working memory). Reading is different in kind, because it builds a foundation shared by many tasks: vocabulary, knowledge, and the ability to follow an argument through a text.

Cognitive function in old age: slower decline in people with more mental activity

In a study that tested 294 older adults every year (for an average of 5.8 years) and examined their brains after death, people who had engaged in more cognitive activities such as reading in early and late life showed a slower decline in cognitive function (Wilson and colleagues, 2013, Neurology). Cognitive activity explained 14% of the variation in decline that brain pathology could not account for.

This is an observational study, however, and reading was only one of the cognitive activities measured. It does not show that reading prevents dementia, but the result is consistent with the idea of cognitive reserve, in which spare capacity built up in the brain compensates for decline.

"Reading fiction boosts empathy" did not replicate

An experiment published in Science in 2013 reported that right after reading a short passage of literary fiction, participants scored higher on a "theory of mind" test of inferring other people's feelings, and it drew wide media coverage (Kidd & Castano, 2013). But in a replication by three labs with 792 participants in total, the group that read literary fiction showed no significant advantage (Panero and colleagues, 2016).

For now, the claim that reading one short piece of fiction boosts empathy is not established. The link between how much fiction someone has read over many years and their understanding of others is a separate question, and the research there is mostly correlational. The more reliable effects of reading are on vocabulary and knowledge.

Paper or screen: which should you read on?

A meta-analysis of studies from 2000 to 2017 (171,055 participants) found that people understood the same text better on paper than on screens, with an effect size of g=−0.21 (Delgado and colleagues, 2018). The gap was larger under time limits and for informational text, and was almost absent for narrative text.

For text you read to research or study, paper is the safe choice, or on a screen, take your time. The link between fragmented smartphone reading and concentration is also covered in the attention span myth and handwriting vs. typing.

In Japan, 6 in 10 people don't read a single book a month

In Japan, the Agency for Cultural Affairs' fiscal 2023 Public Opinion Poll on the Japanese Language (people aged 16 and over, 3,559 valid responses) found that 62.6% read no books in a typical month (including e-books, excluding magazines and manga). 27.6% read 1 to 2 books, 6.0% read 3 to 4, and 3.3% read 5 or more (Agency for Cultural Affairs, 2024). Earlier rounds of the survey used face-to-face interviews, so the results cannot be compared directly, but people who don't read books are now the majority.

At the same time, 75.3% of those who read no books still read text such as social media posts or online articles almost every day. For building vocabulary, what matters is setting aside time for longer, coherent text rather than short posts.

How to check the abilities you've built through reading

Keep in mind that reading mainly builds vocabulary and knowledge, which tend not to show up directly on a nonverbal IQ test that uses only figures. If you still want a guide to your reasoning ability, BrainRank's free IQ test 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

How many IQ points can reading add?: A few points is a reasonable expectation. No study has put a point value on reading alone, but schooling, which includes reading, is estimated to raise IQ by about 1 to 5 points for each additional year (Ritchie and Tucker-Drob, 2018). In a study of identical twins, differences in reading ability also led to later differences in intelligence, but the effects were small to moderate. Reading will not raise your IQ by 10 or 20 points in a short time.
Do comics, e-books, or online articles count?: For building vocabulary and knowledge, the more text you read, the better your odds. The effects shown in research come mainly from reading books of prose, and the effect of reading volume shows up most clearly in vocabulary and reading comprehension. Note, though, that a meta-analysis found comprehension of informational text is somewhat lower on screens than on paper (Delgado and colleagues, 2018, g=−0.21), and the gap widens under time pressure. For text you want to understand thoroughly, reading on paper without rushing is the safe choice.
Is it worth starting to read as an adult?: Yes. The link between reading volume and vocabulary actually grows stronger with age: among college students, reading explained 34% of the variation in oral language skills such as vocabulary (Mol and Bus, 2011). A study that followed 294 older adults found that more cognitive activity in early and late life explained 14% of the variation in cognitive decline not accounted for by brain pathology (Wilson and colleagues, 2013). This is an observational study, however, so it cannot show that reading prevents decline.

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Editorial note & disclaimer

BrainRank Editorial Team

This article was written and edited by the BrainRank Editorial Team with reference to academic literature on psychometrics, including CHC theory and Item Response Theory (IRT). 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 purposes only. They are not medical or clinical assessments, nor official psychological (intelligence) tests.

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