Average IQ by Education Level: The Data, the Selection vs Causation Question, and What the Numbers Actually Mean

The relationship between IQ and educational attainment is one of the strongest in all of behavioral science. With a meta-analytic correlation of approximately r = .56, IQ predicts educational outcomes more strongly than it predicts income (r ≈ .23) and more strongly than most personality traits predict any outcome. When WAIS-IV normative data is broken down by education level, a clear staircase pattern emerges: from IQ 92 (less than high school) to IQ 116 (doctoral degree), average IQ rises with each additional educational credential.

But what do these numbers actually mean? Do they tell us that getting a PhD causes a person's IQ to reach 116? Or that you need IQ 116 to earn a doctorate? The answer to both questions is no — and understanding why requires separating two distinct processes that both contribute to the correlation: selection (higher-IQ people pursue more education) and causation (more education modestly raises measured IQ).

This guide covers the full IQ-by-education data from the WAIS-IV normative sample, the selection vs causation question, the crucial insight about overlapping distributions, and what the education-IQ relationship means for individuals versus populations.

The Data: Average IQ by Education Level

The most methodologically rigorous source for average IQ by education level in the United States is the WAIS-IV standardisation sample — a nationally representative sample of 2,200 adults used by Pearson to norm the Wechsler Adult Intelligence Scale Fourth Edition (published 2008). This sample was carefully stratified to represent the US adult population across age, sex, race/ethnicity, geographic region, and educational attainment.

Source: WAIS-IV Standardization Sample (Wechsler, 2008). n = 2,200 nationally representative US adults.

Several features of this data are worth noting. The range from least educated to most educated is approximately 24 IQ points — a meaningful difference, but one that spans only from the lower Average range to the upper High Average range. PhD holders on average are not in the gifted or Superior range — they are at the 86th percentile, in the High Average classification. The data shows that "average" covers a large portion of all education levels, from high school graduates to bachelor's degree holders. For context on what these IQ ranges mean cognitively and professionally, see our guides on IQ 90 through IQ 116.

The Central Question: Does Education Cause IQ to Rise?

The r ≈ .56 correlation between IQ and educational attainment — one of the strongest in behavioral science — raises an important question: is this correlation evidence that education causes IQ to rise, or that higher-IQ people simply pursue more education? The research answer is: both, but in very different proportions.

Selection (the primary pathway)

Higher cognitive ability predicts academic success at each educational threshold — passing exams, completing coursework, succeeding in competitive admissions processes. This means that each successive educational level filters progressively toward higher cognitive ability. People who complete doctoral programmes were, on average, already cognitively above average before they entered those programmes. The observed IQ differences between education levels are substantially a reflection of this selection process — the fact that higher-IQ people are more likely to pursue and successfully complete each additional level of education.

This is why you cannot conclude from the PhD average of IQ 116 that earning a PhD will give you an IQ of 116. If you begin a doctoral programme with IQ 105, you are not likely to emerge with IQ 116. You will emerge with approximately IQ 105 plus any modest causal educational effect — which brings us to the second pathway.

Causation (the secondary pathway)

Education does have a genuine, if modest, causal effect on measured IQ. The most rigorous quantification comes from a 2018 meta-analysis by Ritchie and Tucker-Drob, published in Psychological Science, which synthesised results across studies involving over 600,000 participants. Using a range of methodological approaches designed to isolate the causal effect of education from selection (including natural experiments, comparative datasets, and regression discontinuity designs), they estimated that each additional year of schooling causes approximately 1–5 IQ points of improvement in measured cognitive ability.

The mechanisms for this causal effect are plausible: education expands vocabulary and knowledge (increasing crystallised intelligence / Gc), practises specific cognitive skills measured by IQ tests (logical reasoning, verbal analysis, numerical thinking), and may expand working memory through sustained cognitive engagement. The effect appears strongest for fluid intelligence measures when educational quality is high and content is genuinely cognitively demanding.

The practical implication: education genuinely builds some of the cognitive capacity that IQ tests measure. It is not purely a proxy for pre-existing cognitive ability. But the selection effect is substantially larger than the causal effect — which is why the IQ averages by education level look like a selection ladder as much as a learning staircase.

Why Averages Are Not Thresholds: The Overlap Problem

The most important practical point about IQ-by-education data is also the one most frequently missing from popular coverage: the IQ distributions across education levels overlap substantially. The average IQ for a PhD holder is approximately 116 — but this does not mean all PhD holders have IQ 116 or above, or that PhD programmes are closed to people below this average.

Within each educational category, IQ varies across a range of approximately 40–50 IQ points. Many high school graduates have IQ scores above 120. Many college graduates have IQ scores below 100. A person with IQ 100 can earn a doctorate through sustained effort, strategic focus, and effective study methods — and many do. A person with IQ 130 who drops out of high school for economic or personal reasons will not appear in the PhD average despite having the cognitive capacity that would have predicted doctoral completion under different circumstances.

This point matters for how to interpret the data. The averages describe group-level patterns — the fact that higher educational levels tend to filter toward higher cognitive ability. They do not define individual ceilings or thresholds. IQ is one predictor of educational outcomes, not a deterministic gate.

The IQ-Education Correlation in Context

Comparing the IQ-education correlation (r ≈ .56) to other IQ correlations puts the education relationship in perspective:

The IQ-education correlation is the strongest documented IQ-outcome relationship. This makes intuitive sense: educational systems are built around the cognitive skills that IQ tests measure. Verbal reasoning, logical analysis, abstract pattern recognition, working memory — these are exactly what academic work demands and what IQ tests assess. Education and IQ are measuring overlapping constructs from different directions. For context on both relationships, see our guides on IQ and income and average IQ by profession.

International Variation and Confounds

The WAIS-IV data above is US-specific. IQ-by-education patterns vary internationally for several reasons:

Educational access and selection rate. In countries where university attendance is highly selective (a small minority of young people attend), the average IQ of university graduates is higher than in countries where university attendance is near-universal. As any country's higher education participation rate rises, the average cognitive ability of its graduates moves toward the overall population mean — because a broader and more cognitively diverse group is now attending.

Educational quality. The causal effect of education on IQ (1–5 points per year) varies with educational quality. Countries with high-quality, cognitively demanding schooling produce stronger IQ gains from education than countries with rote-based or underfunded educational systems.

Socioeconomic confounding. Family socioeconomic background predicts both IQ and educational attainment independently. The IQ-education correlation partially reflects the fact that children from higher-SES families tend to have both higher IQ (for genetic and environmental reasons) and more access to extended education. Studies that do not control for SES overestimate the pure IQ-education relationship.

Full Reference Table

For context on what specific IQ scores in these ranges mean, see our guides on IQ 90, IQ 105, IQ 108, IQ 112, and IQ 116. For context on how education-level IQ relates to professional group averages, see our average IQ by profession guide.

Average IQ by education level rises from approximately IQ 92 (less than high school) to IQ 116 (doctoral degree) — a 24-point range based on WAIS-IV normative data. This pattern reflects both selection (higher-IQ people pursue more education) and causation (education modestly raises measured IQ by approximately 1–5 points per year, per Ritchie and Tucker-Drob, 2018). The IQ-education correlation (r ≈ .56) is the strongest documented IQ-outcome relationship. But as with all group averages, the distributions overlap substantially: many high school graduates have higher IQs than many PhD holders, and educational level is not an IQ threshold but a probabilistic predictor. The data describes population-level tendencies. Individual variation always matters more than the average.

Find out where your own cognitive profile sits with our free IQ test — no registration, results in under 20 minutes. For related guides, see our average IQ by profession and IQ and income guides. For the full IQ scale context, see our IQ scale explained.

Frequently Asked Questions

What is the average IQ of a college graduate?

Based on WAIS-IV normative data, individuals with a bachelor's degree average approximately IQ 107 — 7 points above the population mean. This is an average across a wide range: many college graduates have IQs below 100, and many people with IQs above 120 have no college degree.

What is the average IQ for a PhD?

Individuals with doctoral degrees average approximately IQ 116 — High Average classification, approximately the 86th percentile. This is not a threshold — people across a wide IQ range earn doctorates, and the average reflects both the selection of higher-IQ people into advanced education and the modest causal effect of education on IQ.

Does education increase IQ?

Yes, modestly. A 2018 meta-analysis by Ritchie and Tucker-Drob (*Psychological Science*, n = 600,000+) estimated that each additional year of schooling causes approximately 1–5 IQ points of improvement in measured cognitive ability. However, the primary driver of the IQ-education correlation is selection: higher-IQ people pursue more education, not mainly because education raises IQ.

What is the correlation between IQ and education?

The IQ-education correlation is approximately r = .56 — the strongest documented IQ-outcome relationship, stronger than the IQ-income correlation (r ≈ .23) and among the most robust associations in behavioral science.

Does a higher education level mean a higher IQ?

On average, yes — IQ rises with education level. But the distributions overlap substantially. A high school graduate at the 90th percentile has a higher IQ than many PhD holders at the 50th percentile of their group. Education level is a population-level predictor of cognitive ability, not an individual-level IQ determinant.