What is IQ?
IQ (intelligence quotient) is a standardized score that compares your performance on reasoning tasks with that of a reference group. On the modern scale, the mean is 100 and the standard deviation is 15. About 68% of people score between 85 and 115.
How to read the scale
| IQ | Range | Of the population |
|---|---|---|
| 130 or higher | Very high | ≈ 2% |
| 120 to 129 | Above average | ≈ 7% |
| 110 to 119 | High average | ≈ 16% |
| 90 to 109 | Average | ≈ 50% |
| 80 to 89 | Low average | ≈ 16% |
| 70 to 79 | Below average | ≈ 7% |
| Below 70 | Very low | ≈ 2% |
What is a percentile?
A percentile is the percentage of the reference group that you outscored. The 75th percentile means you scored higher than about 75% of people. An IQ of 115 corresponds roughly to the 84th percentile.
Why does every result have a margin of error?
No test measures with perfect precision. Sleep, attention, anxiety and even screen size affect performance. That is why we show a 90% confidence interval: the range in which your result would probably fall if you took equivalent tests again. Be wary of sites that show an exact number with no margin of error.
Does IQ change over time?
IQ tends to be relatively stable in adulthood, but it is not fixed. Education, health, sleep and familiarity with the type of task all influence the result. Practicing a specific type of question improves performance on that task. The improvement in general intelligence is much more modest, and researchers still debate how much it is worth.
Celebrities and IQ
You will find lists of “Einstein’s IQ” or the IQs of famous business people. They are almost always made-up numbers, because most of these people never took a published test. That is why we do not make this kind of comparison.
Online test vs. psychological assessment
Formal intelligence assessments (for example, for a diagnosis or a professional report) are carried out by licensed psychologists using validated instruments. An online test like ours gives a useful estimate for self-discovery, but it does not replace that assessment.