Average American IQ: What Is the Average IQ in the US and by State?

Finding different IQ averages on different websites can leave you wondering which number to trust. The average American IQ is generally described as around 100 because widely used intelligence tests set their average at 100 within the population used to establish their norms. That number is a reference point for interpreting scores, not the result of a new nationwide survey conducted every year.

State rankings need a closer look. Some familiar estimates come from educational assessment data rather than individual IQ tests administered to a representative sample of every state’s residents. A recent date in a headline does not necessarily mean the underlying measurements are recent.

Below, we’ll explain why published averages differ, examine state estimates and their limitations, and clarify what an individual score means. If you’re comparing your own result, understanding the test behind that number is a useful place to start.

• Standardized IQ tests place average performance at 100 within their reference populations, providing context for interpreting individual test results;
• historical state IQ estimates in this article derive from school achievement data and do not represent current population-wide testing;
• percentiles describe relative standing within a comparison group, while confidence intervals communicate measurement uncertainty surrounding an individual IQ score;
• professional assessments combine test results with developmental history, observations, and everyday functioning to investigate specific learning or practical difficulties.

What Is the Average American IQ?

On most widely used IQ tests, 100 marks the center of the reference scale. That is why the average American IQ is usually described as around 100. A study of a particular US sample can produce a different average without contradicting how the scale works.

Why IQ Tests Use an Average of 100

An IQ score needs a comparison group to mean anything. During test development, researchers establish norms that allow an individual’s performance to be interpreted relative to a reference population. Age matters: a child’s performance is compared with age-appropriate expectations, rather than judged against an adult’s performance.

Think of 100 as the center of the scoring scale, not 100 correct answers or a percentage of someone’s intellectual potential. The American Psychological Association explains that norm-referenced tests evaluate performance against established comparison standards. A comprehensive assessment then combines test results with other relevant information.

For example, imagine a parent reading a child’s assessment report beside an online state ranking. Both documents might use numbers near 100, but they answer different questions. The report describes the child’s assessed performance; the ranking summarizes a geographic group using a particular estimation method.

Why Published US Averages Differ

Before comparing two averages, check what each source actually measured. The phrase “average IQ” can refer to several different kinds of numbers.

Published state estimates, for instance, have used educational assessment results to derive IQ estimates. Those figures should not be presented as though researchers individually tested every state’s adult population.

Two averages are meaningfully comparable only when their methods and populations are sufficiently similar. If a website gives a precise number without identifying its test, sample, or source, that precision alone offers little reason to trust it.

Average IQ by State: Estimates and Their Limits

Published figures for average IQ by state are estimates whose meaning depends on the underlying data. The historical figures below come from Michael McDaniel’s 2006 study, which used public-school achievement results. They should not be read as current measurements of every state’s population.

Where State IQ Estimates Come From

McDaniel used National Assessment of Educational Progress results in reading and mathematics for fourth- and eighth-grade public-school students. Results from multiple assessment years were converted to an IQ-style scale and combined into state estimates. The assessment years extended from 1990 through 2005, with availability varying by subject, grade, and state.

NAEP itself measures educational achievement. The National Center for Education Statistics explains that it reports group results rather than individual student scores. Using those results to estimate IQ adds a research interpretation; it does not turn the original assessment into a clinical intelligence test.

There are later estimates, too. Bryan Pesta’s 2022 study combined information from NAEP and the Program for the International Assessment of Adult Competencies, or PIAAC. That is a separate dataset with a different method, so its values should not be mixed into the historical list below. A newer publication also needs to be checked for the dates of its underlying measurements.

Published Estimates for All 50 States

The following alphabetical list reproduces the estimated state IQ column in Table 3 of McDaniel’s study. It provides a reference for recognizing the historical numbers still circulated online.

• Alabama: 95.7;
• Alaska: 99.0;
• Arizona: 97.4;
• Arkansas: 97.5;
• California: 95.5;
• Colorado: 101.6;
• Connecticut: 103.1;
• Delaware: 100.4;
• Florida: 98.4;
• Georgia: 98.0;
• Hawaii: 95.6;
• Idaho: 101.4;
• Illinois: 99.9;
• Indiana: 101.7;
• Iowa: 103.2;
• Kansas: 102.8;
• Kentucky: 99.4;
• Louisiana: 95.3;
• Maine: 103.4;
• Maryland: 99.7;
• Massachusetts: 104.3;
• Michigan: 100.5;
• Minnesota: 103.7;
• Mississippi: 94.2;
• Missouri: 101.0;
• Montana: 103.4;
• Nebraska: 102.3;
• Nevada: 96.5;
• New Hampshire: 104.2;
• New Jersey: 102.8;
• New Mexico: 95.7;
• New York: 100.7;
• North Carolina: 100.2;
• North Dakota: 103.8;
• Ohio: 101.8;
• Oklahoma: 99.3;
• Oregon: 101.2;
• Pennsylvania: 101.5;
• Rhode Island: 99.5;
• South Carolina: 98.4;
• South Dakota: 102.8;
• Tennessee: 97.7;
• Texas: 100.0;
• Utah: 101.1;
• Vermont: 103.8;
• Virginia: 101.9;
• Washington: 101.9;
• West Virginia: 98.7;
• Wisconsin: 102.9;
• Wyoming: 102.4.

Within this historical dataset, Massachusetts has the highest estimate and Mississippi the lowest. That comparison describes this dataset, not a verified ranking of residents’ abilities today.

How to Read State Comparisons

Start with the people represented. A sample designed to describe public-school students is not automatically representative of adults, private-school students, or everyone else living in a state. Before treating any estimate as a population-wide finding, ask whether the sampling and estimation methods support that interpretation.

Next, separate a group average from an individual result. Imagine someone moving from California to Massachusetts. The difference between the two listed estimates is not an increase that should be added to that person’s IQ score. Their address supplies no substitute for an individual assessment.

Small differences also deserve caution. NCES explains that one state can have a numerically higher NAEP score than another without the difference being statistically significant. Sorting estimates to one decimal place creates a precise-looking order, but the order alone does not show whether neighboring positions are meaningfully different.

The same caution applies to explanations. An achievement comparison does not establish why a difference exists, and NAEP is not designed to identify the causes of differences in performance. A ranking therefore cannot, by itself, tell you which school policy, family circumstance, or educational experience produced a particular result.

Finally, averaging the 50 state figures gives each state equal weight, regardless of population. That answers a different question from estimating the average across individual US residents. Population weighting would change the calculation, but it would not fix an unrepresentative sample or outdated measurements.

For any state ranking, check four things: the original study, the assessment years, the people represented, and the estimation method. Those details tell you far more about what the numbers mean than the year displayed in the headline.

What Does Your IQ Score Actually Mean?

An IQ score describes your performance relative to the reference group for a particular test. To interpret it, you need the test’s norms, the uncertainty around the result, and the broader assessment findings. A state ranking cannot provide that context.

Understanding Score Ranges and Percentiles

On a scale with a mean of 100 and a standard deviation of 15, scores from 85 to 115 fall within one standard deviation of the mean. Under the normal distribution used to interpret that scale, this interval contains approximately 68% of scores. Descriptive labels such as “average” or “low average” depend on the test’s classification system, so check the wording in your report.

A percentile describes relative standing, not the percentage of questions answered correctly. The 50th percentile is the midpoint of the reference distribution. A score at the 84th percentile means performance at or above roughly 84% of the relevant comparison group.

These numbers answer different questions: the IQ score places performance on a standardized scale, while the percentile expresses its relative position.

Reading the Score in Context

An assessment report may also include a confidence interval, which communicates uncertainty associated with measurement. For example, Pearson’s sample WISC-V report gives a Full Scale IQ of 97 with a 95% confidence interval of 91 to 103. Treating 97 as an exact, unchanging quantity would overlook that uncertainty.

The profile matters, too. Imagine a parent seeing stronger visual-spatial performance alongside a lower working-memory score. That parent might ask, “Could this pattern help explain why my child handles visual puzzles comfortably but struggles to keep track of spoken instructions?”

A psychologist considers the results alongside history, observations, and other assessment information. Ask what the findings explain, what remains uncertain, and which recommendations follow from the complete evaluation.

Getting a Reliable Cognitive Assessment

A useful cognitive assessment should answer a specific question about learning or everyday functioning. The American Psychological Association describes assessment as a process that combines test results with interviews, observations, and relevant records. A score displayed at the end of a quiz provides much less context.

Checking an Online Test’s Claims

Before trusting an online result, look for published information about its comparison sample, age norms, reliability, and validity. Reliability describes how consistently a test measures performance under comparable conditions. Validity asks whether the evidence supports what the test claims to measure and how its results are used.

Ask who developed the test and whether its documentation supports the claims on its homepage. A detailed-looking certificate or decimal score does not answer those questions. If the site offers no technical explanation, avoid using its result to make decisions about education, employment, or clinical care.

When a Professional Evaluation Makes Sense

Persistent learning difficulties, problems managing familiar tasks, or unanswered questions about an existing assessment are reasons to discuss an evaluation with a qualified psychologist. Bring concrete examples, such as repeatedly losing track of multistep instructions, rather than only an online score.

Under the DSM-5-TR framework, intellectual developmental disorder, also called intellectual disability, involves limitations in intellectual and adaptive functioning that begin during the developmental period. Adaptive functioning includes conceptual, social, and practical everyday skills. A low score alone does not establish the diagnosis.

Before booking, ask about the clinician’s assessment experience, the questions testing will address, fees, and insurance coverage. You should also know whether the service includes a written report and a feedback appointment.

This article is informational and does not replace professional assessment. For a mental health crisis in the United States, call or text 988 (Suicide & Crisis Lifeline); if in immediate danger, call 911.

The average American IQ is commonly described as around 100, but any published figure needs context: the test, the comparison group, and the age of the data. State estimates answer a different question and cannot tell you what an individual is capable of. When reading your own results, look beyond the headline score to the explanation and recommendations in the report. If learning or everyday tasks remain difficult, a qualified psychologist can assess those concerns and discuss appropriate support.

References

1. OpenStax, Rice University. Psychology 2e: Measures of Intelligence. 2020.

2. American Psychological Association. Understanding Psychological Testing and Assessment. Updated August 18, 2022.

3. McDaniel, M. A. Estimating State IQ: Measurement Challenges and Preliminary Correlates. Intelligence, 34(6), 607-619. 2006. Bibliographic record available through ERIC.

4. Pesta, B. J. Updated IQ and Well-Being Scores for the 50 U.S. States. Journal of Intelligence, 10(1), 15. 2022.

5. National Center for Education Statistics. Students: What Is NAEP? Publication date not specified.

6. National Center for Education Statistics. Statistical Significance. Publication date not specified.

7. American Psychiatric Association. What Is Intellectual Disability? Publication date not specified.

Frequently Asked Questions

Is an IQ of 100 average in the United States?

Yes. Widely used IQ tests set their normative average at 100, making that score a reference point for interpreting individual performance. A published estimate for a particular US sample may differ because it reflects the people tested and the method used.

Is an IQ of 85 necessarily a sign of a disability?

No. A score of 85 alone does not establish a disability or explain someone's support needs. Diagnosing intellectual disability requires evaluating intellectual and adaptive functioning, developmental history, and clinical findings. The test's measurement uncertainty also matters when interpreting an individual result.

Can an online IQ test replace a professional assessment?

A self-administered online quiz cannot replace a comprehensive professional assessment. Check whether the test publishes evidence about its norms, reliability, and intended use. A psychologist interprets appropriate test results alongside history and other information to answer specific questions about learning or functioning.

Are IQ scores compared within age groups?

Widely used individual intelligence tests use age-based norms to interpret performance. A child's score therefore reflects comparison with an appropriate age group, rather than direct comparison with adults. Check the test's name, edition, and normative information when reading a report.

Does moving to a higher-ranked state change your IQ?

Moving does not automatically change your IQ to match a state's estimate. State rankings describe groups using a particular dataset and method. They cannot establish your individual abilities or predict how your own test performance will change after a move.

Why do some recent state rankings use older data?

A website can update its headline or presentation while retaining figures from an older study. The familiar estimates reproduced in this article come from research published in 2006. Check the original study and assessment years before treating a recently updated ranking as new evidence.