Average IQ by Age and Country

What is the average IQ?

The average IQ is 100. Test makers build the scale that way. They give a test to a large sample, then convert the raw scores so that the middle is 100 and one standard deviation is 15 points.

That gives a simple rule of thumb. About two thirds of people score between 85 and 115. About 95 in 100 score between 70 and 130. Fewer than 3 in 100 score above 130 or below 70.

Average IQ by age

The average IQ is 100 at every age, because your score compares you with people your own age. A ten year old and a seventy year old can both score 100 and have very different raw results on the same puzzles.

The raw ability behind the score does change over a lifetime. Speed and the ability to handle new puzzles tend to peak in early adulthood and drift down later. Knowledge and vocabulary keep growing for longer. Tests that report an age adjusted score hide those shifts on purpose.

This site does not adjust for age. Our test is written for teenagers and adults, and the scale is a fixed table. See the method page for how the score is built.

Average IQ by country

You will find lists that rank countries by average IQ. We do not publish one, because we do not trust the numbers behind them.

• Different tests. The studies behind the lists use different tests, years and sample sizes, then merge the results.
• Gaps filled by guesses. For many countries there is little or no good data, so the figure is an estimate from nearby countries.
• Scores follow schooling and health. Years in school, nutrition, health care and practice with tests all raise scores. A national average mostly reflects those conditions, not anything fixed about a population.
• The scale is re-set for each population. A country's tests are normally scaled so its own average is 100, which means a raw national comparison needs extra steps that add error.

If you read a table of country averages somewhere, check who made it, which tests it uses and which years it covers before you believe it.

The Flynn effect: why scores rose over the 20th century

For much of the 20th century, raw scores on IQ tests rose in many countries, by roughly three points per decade. This is called the Flynn effect, after the researcher who documented it. Because of it, tests have to be re-normed every so often to keep the average at 100.

No one believes people became three times as smart in a century. The usual explanations are better schooling, better nutrition, smaller families and more exposure to abstract puzzles. In some countries the rise has slowed or reversed in recent years.

Where do I fit?

If you took our test, your result is on the IQ score chart, with the label for your range. A typical result is anything from 90 to 109.