Average IQ in the United States: What Is America's IQ?

The average IQ in the United States is approximately 98 — just below the global norm of 100. If you've heard that 100 is the universal average, that's technically correct: IQ tests are designed so that 100 represents the median score at the time the test was standardized. Because the US re-normed its tests more recently than some other countries, American scores sit fractionally below the theoretical 100 midpoint on current global comparisons. In practical terms, a score of 98 is statistically indistinguishable from average.

To understand where any IQ score sits on the distribution, see our complete IQ score ranges guide or our IQ percentile chart.

The Flynn Effect: How American IQ Has Changed

One of the most striking findings in intelligence research is the Flynn Effect— the long-term rise in raw IQ scores that has been documented across virtually every country that has collected data over multiple decades. In the United States, average IQ scores increased by approximately 3 points per decade from the 1930s through the late 1990s — a total rise of roughly 20–25 points over that 70-year period.

The drivers of this rise include improved nutrition (particularly in early childhood), rising educational attainment, better access to healthcare, and the growing familiarity with abstract and visual thinking required by modern life. IQ tests were not getting easier — people genuinely became better at the cognitive tasks these tests measure.

However, research published since 2010 suggests the Flynn Effect has plateaued in the United States and may even be reversing slightly. Studies from Norway, Denmark, Finland, and the UK show modest IQ declines since roughly 2000 in some demographic groups. In the US, the evidence is mixed — some studies show stable scores, others show slight declines, particularly in verbal reasoning. Proposed explanations include changing educational quality, increased screen time displacing complex reading, and potential nutritional factors including lead exposure in earlier cohorts aging out of the population.

Average IQ by Education Level

IQ and educational attainment are strongly correlated — not because education directly raises IQ dramatically, but because higher-IQ individuals are more likely to pursue and complete advanced education. The following are average IQ estimates by highest level of education completed, based on meta-analyses of US psychometric data:

Important caveat: these are population averages with wide distributions. Many people without college degrees have very high IQs, and not all doctoral graduates score above 120. The correlation between education and IQ is real but imperfect — socioeconomic access, motivation, and circumstances influence educational attainment independently of cognitive ability.

Average IQ by Age Group

IQ scores are always measured relative to one's age group — that's how IQ tests are designed. A 10-year-old scoring 100 and a 40-year-old scoring 100 have both performed at the median for their respective age cohorts. Raw cognitive abilities follow a predictable developmental arc:

• Childhood (5–12): Processing speed and fluid intelligence develop rapidly
• Adolescence (13–19): Peak development of most cognitive abilities
• Young adulthood (20–35): Peak fluid intelligence (novel problem-solving)
• Middle age (35–60): Crystallized intelligence (accumulated knowledge) continues to grow even as fluid intelligence plateaus
• Older adulthood (60+): Processing speed declines; wisdom and crystallized knowledge partially compensate

For detailed analysis by age, see our guide on what IQ actually measures.

Average IQ by State

Several researchers have estimated average IQ by US state using educational achievement data, SAT/ACT scores, and direct IQ testing samples. The variation across states is real but relatively modest — typically within 8–12 IQ points from the lowest to the highest state. States with higher average incomes, better-funded public schools, and lower rates of childhood poverty tend to score higher. States with higher rates of childhood lead exposure, food insecurity, and underfunded schools tend to score lower.

Consistently higher-ranking states include Massachusetts, Connecticut, New Hampshire, Vermont, and New Jersey. States consistently ranked lower include Mississippi, Louisiana, New Mexico, and Alabama. These differences are not fixed — they respond to policy changes, economic conditions, and educational investment over time.

We have individual pages for each US state's average IQ. Explore your state's data to see how local education and economic factors shape cognitive outcomes.

How the US Compares to Other Countries

Internationally, the US ranks approximately 24th to 30th in average IQ depending on the study and methodology. The most comprehensive recent analysis (Lynn & Becker, 2019) places the US at approximately 98, consistent with most Western nations.

For a full breakdown, see our average IQ by country page.

What Drives Differences in National and Regional IQ?

The question of why IQ averages differ across countries and regions is one of the most actively debated topics in intelligence research. Current scientific consensus points to several environmental factors as primary drivers:

• Educational quality and access: Countries with better-funded, more equitable schools produce higher average scores. This is the single strongest predictor of national IQ.
• Nutrition, particularly in early childhood: Iodine deficiency alone can reduce IQ by 10–15 points. Iron, folate, and omega-3 fatty acids are also critical for brain development. The Flynn Effect in developed countries closely tracks improvements in childhood nutrition.
• Healthcare and reduction of infectious disease: Childhood illness — even subclinical infections — can disrupt cognitive development. Countries with better childhood healthcare consistently score higher.
• Reduction of toxin exposure: The removal of lead from gasoline and paint in the 1970s–1980s is estimated to have raised average US IQ by 2–5 points. Lead exposure disproportionately affects lower-income communities.
• Socioeconomic equality: Countries with lower income inequality tend to score higher on average, as more children have access to cognitive enrichment.

Genetic differences between national populations are not supported by current evidence as a meaningful driver of average IQ differences. The large Flynn Effect gains over mere generations — too fast for genetic change — demonstrate that these differences are environmental in nature.

Frequently Asked Questions

What is the average IQ in the United States?

Approximately 98 — just below the theoretical global norm of 100. In practical terms, this is statistically equivalent to average. Most Americans score between 85 and 115.

Is the US IQ average declining?

The Flynn Effect — the long rise in US IQ scores from the 1930s to 2000 — appears to have plateaued. Some studies suggest a modest decline in verbal reasoning since 2000, though the evidence is mixed. The causes are debated among researchers.

Which US state has the highest average IQ?

States with the highest estimated averages tend to be Massachusetts, Connecticut, and New Hampshire — states with high educational attainment and lower childhood poverty rates. Estimates vary significantly between studies.

How does US IQ compare to other countries?

The US ranks approximately 24th–30th globally, behind East Asian countries (Singapore, Japan, South Korea) and comparable to most Western European nations. These differences primarily reflect educational quality and childhood nutrition rather than inherent cognitive differences.

Want to know how your score stacks up against the US average? Take our free IQ test, or explore what your IQ score range means.