My IQ TestAverage IQ in the UK: Data, Trends and Context
The average IQ in the United Kingdom is about 100, and the UK is often used as the reference point for international comparisons. British cohort studies are among the best long-term sources on how intelligence develops and changes.
Why the UK anchors international scales
Raven's Progressive Matrices, developed by British psychologist John Raven in 1938, were normed extensively on UK samples. When Richard Lynn compiled national averages, he set British norms as 100 and expressed other countries relative to them. That is why the UK nearly always appears at exactly 100 in such tables.
What British cohort studies tell us
The UK has unusually rich long-term data. The 1946 National Survey of Health and Development, the 1958 National Child Development Study and the 1970 British Cohort Study tracked thousands of people from birth. In Scotland, almost every child born in 1921 and 1936 sat the same test at age 11, and the Lothian Birth Cohorts later retested many of them in old age.
These studies show that childhood test scores predict later education, income and even health and longevity — but also that education and health in adulthood shape how well thinking skills hold up.
Is the UK's average changing?
British scores rose through most of the twentieth century. Some studies of teenagers since the 1980s report small declines on certain Piagetian and spatial tasks, which researchers link to changes in schooling, reading and test familiarity rather than biology.
| Measure | Typical figure |
|---|---|
| Average adult IQ | ≈100 |
| British Mensa entry | Top 2% (≈130+ on a 15-SD scale) |
| Correlation of age-11 and age-77 scores (Lothian) | ≈0.66 |
IQ, GCSEs and the 11-plus
GCSE results correlate strongly with cognitive ability at age 11 — around 0.8 in a large study by Ian Deary and colleagues — yet effort, teaching and attendance account for much of the remaining variation. The 11-plus exam used by grammar schools includes verbal and non-verbal reasoning items similar to those on IQ tests.
See how the UK compares with its neighbours in our guide to average IQ in Europe, compare with the US average, or try our free test.
Common questions
What is the average IQ in the UK?
About 100. The UK is the reference point for many international IQ comparisons.
What score do you need for British Mensa?
A score in the top 2% on a supervised test, roughly 130 or more on a scale with a standard deviation of 15.
About the author
Dr. Elena Marsh — Elena has spent over a decade studying intelligence measurement and test construction, with a focus on fluid reasoning and fair item design.
Reviewed by Prof. Daniel Okafor — Daniel reviews item statistics and norming assumptions for our test and guides.
Sources and further reading
- Deary, I. J., Strand, S., Smith, P., & Fernandes, C. (2007). Intelligence and educational achievement. Intelligence, 35(1), 13–21.
- Deary, I. J., et al. (2013). The Lothian Birth Cohort 1936. International Journal of Epidemiology, 42(5).
- Raven, J. (2000). The Raven's Progressive Matrices: Change and stability over culture and time. Cognitive Psychology, 41, 1–48.
- Flynn, J. R. (2009). Requiem for nutrition as the cause of IQ gains: Raven's gains in Britain 1938–2008. Economics & Human Biology, 7(1).