Average IQ by country

The short answer

There is no reliable average IQ for most countries. IQ tests are calibrated so that each country's own average is 100, and nobody has given the same IQ test to a fair sample of every country. The "national IQ" lists online mostly copy one dataset whose figures often rest on a few small, old studies.

The best comparable measure of reasoning across countries is the OECD's PISA test, taken by about 15-year-olds in 91 countries and economies (2025 round, results published 8 September 2026). The top ten in maths: four Chinese provinces (B-S-J-Z), Singapore, Macao, Taiwan, Japan, South Korea, Hong Kong, Estonia, Switzerland, United Kingdom. The OECD averages were 463 in maths and 482 in science, the lowest yet.

PISA 2025 scores by country

Sorted by science, the main subject of the 2025 round. Scores are points on PISA's own scale, not IQ points.

Source: OECD, PISA 2025 Results, Volume I. "B-S-J-Z (China)" is Beijing, Shanghai, Jiangsu and Zhejiang only, not all of China. Some countries tested only part of their territory. Countries that did not take part (including India and most of Africa) have no score.

Why we don't publish a "national IQ" list

The widely shared figures go back to a dataset by Richard Lynn and Tatu Vanhanen (2002), later extended. For many countries the number comes from one or two small studies, some of a few dozen children, often decades old and using tests translated on the spot; missing countries were filled in by averaging their neighbours. Psychologists have pointed out that these samples cannot stand for whole populations, so the rankings say more about the data than about the people.

What large studies do show is that test scores move with schooling, health, nutrition and income, and rise as countries develop. That is the Flynn effect: average scores rose by about 3 IQ points a decade during the 20th century (Trahan and others, 2014), far too fast for genes to explain.

Questions

Which country has the highest average IQ?

No country has a reliable national IQ average: the tables that circulate online mix small, unrepresentative samples taken decades apart. On the best comparable test, PISA 2025, the top scorers in maths were four Chinese provinces (Beijing, Shanghai, Jiangsu and Zhejiang), Singapore, Macao, Taiwan, Japan, South Korea and Hong Kong.

Where do the "average IQ by country" numbers come from?

Most copy a dataset started by Richard Lynn and Tatu Vanhanen in 2002 and updated since. Many of its national figures rest on one or two small studies, sometimes of a few dozen children, and gaps were filled by guessing from neighbouring countries. Researchers have criticised the sampling and the methods, so we do not republish those numbers.

What is the average IQ in the United States or the UK?

IQ tests are normed so that the average in the country where they are calibrated is 100, so the average American or British adult scores about 100 on tests normed in their own country. On PISA 2025, the United Kingdom scored 488 in maths and 511 in science, and the United States 463 and 502, against OECD averages of 463 and 482.

Can I convert PISA scores into IQ?

Not honestly. PISA measures what 15-year-olds can do in maths, science and reading after years of school, so it reflects schooling, language and poverty as much as reasoning. It uses its own scale (the OECD average was set near 500). Any "IQ equivalent" would be made up.

Why do countries score so differently?

The largest studies point to schooling (how many years and how good), nutrition and health, family income and how familiar children are with test-style questions. Scores also rise as countries develop: average test performance rose by about 3 IQ points a decade across the 20th century (the Flynn effect).