The IQ scale and the average IQ, explained
An IQ score tells you where you sit compared with everyone else. Here is how to read one.
A bell curve, by design
IQ tests are scaled so that the average is 100 and the standard deviation is 15. That means about 68% of people score between 85 and 115, about 95% between 70 and 130, and only about 2% above 130.
What each range is called
| Score | Range | Share of people |
|---|---|---|
| 130+ | Very superior | about 2% |
| 120 to 129 | Superior | about 7% |
| 110 to 119 | High average | about 16% |
| 90 to 109 | Average | about 50% |
| 80 to 89 | Low average | about 16% |
| 70 to 79 | Below average | about 7% |
| Below 70 | Well below average | about 2% |
What is the average IQ?
100, by design. Every modern IQ test is scaled so that the average person in the group it was normed on scores 100, with a standard deviation of 15. That is why the average IQ is 100 in the UK, in Germany, or anywhere a test was normed on the local population.
League tables of average IQ by country are built from different tests, samples and years that do not compare well, so treat them with real caution.
What do IQ scores of 120, 130 and 140 mean?
An IQ of 120 is higher than about 91% of people. 130 is higher than about 98%, the usual entry point for high-IQ societies. 140 is higher than about 99.6%, roughly one person in 250. Every test has a margin of error of a few points, so read a single score as a range.
What IQ is considered genius?
There is no scientific cut-off. In everyday use, a genius-level IQ usually means 140 or more. Psychologists prefer plainer terms such as very superior for 130 and above, and they never judge a person by one number.
What IQ do you need for Mensa?
Mensa accepts people who score in the top 2% on an approved, supervised intelligence test. On the usual scale that is about 130. An online result, ours included, cannot be used to join, but it can tell you whether a supervised test is worth trying.
What was Einstein's IQ?
Nobody knows. Einstein never took an IQ test, and figures such as 160 are modern guesses. The same is true of most famous names you see with an IQ attached.
Reading a single score
A score is a snapshot. Sleep, stress and familiarity with the puzzle types all move it by a few points, so treat any one result as a range rather than an exact value.
Online tests are estimates. A clinical assessment, such as the WAIS, is given one to one by a psychologist and covers more abilities, including verbal ones. Use an online result for curiosity and practice, not for decisions about school, work or health.
Reasoning can be practised. Familiarity with matrix puzzles and number series raises scores on those puzzles, which is worth knowing when you compare results over time.