There is no scientific definition of a genius IQ. No major test, including the WAIS-5, WISC-V or Stanford-Binet Fifth Edition (SB5), has a category called genius. In everyday use, people usually mean a score of about 140 or above, which roughly 1 in 260 people would reach. Schools and organizations that identify gifted people more often use a threshold around 130, the top 2 to 3 percent.
A high IQ is a score on a test of reasoning, knowledge and mental speed. Genius, in the sense people mean when they talk about Einstein or Mozart, is about extraordinary creative achievement. The two are related but they are not the same thing.
Where the word genius came from in IQ testing
The link between IQ and genius is largely the work of Lewis Terman at Stanford, who adapted Binet's test into the Stanford-Binet in 1916. In early score tables, Terman described scores above 140 as "near genius or genius". He then named his famous long-term study of high-scoring children Genetic Studies of Genius. The label stuck in popular culture long after test publishers dropped it.
Today's manuals use descriptive bands instead, and the wording varies between tests and editions. A score of 130 or above might be called "Very Superior" in one edition and "Extremely High" or "Very High" in another. None of them treat any score as proof of genius. For the full set of bands, see our guide to IQ score ranges.
How rare is a genius IQ score
IQ scores are scaled so that the population has a mean of 100 and a standard deviation of 15, following a normal distribution. That lets you compute how rare any score is. The figures below are the mathematics of the bell curve; real test data at the extremes are less tidy, as explained in the next section.
| IQ score (or higher) | Standard deviations above mean | Share of population | Roughly 1 in |
|---|---|---|---|
| 115 | 1 | 15.9% | 6 |
| 130 | 2 | 2.3% | 44 |
| 135 | 2.33 | 1.0% | 100 |
| 140 | 2.67 | 0.38% | 260 |
| 145 | 3 | 0.13% | 740 |
| 150 | 3.33 | 0.04% | 2,300 |
| 160 | 4 | 0.003% | 31,600 |
To put that in perspective: in a city of 1 million, the math predicts about 23,000 people at 130 or above, about 3,800 at 140 or above, and roughly 30 at 160 or above.
Why scores above 145 are hard to trust
The higher the score, the less the number means. There are three reasons.
- Too few people to compare against. A test's norm sample typically has a few thousand people, split across age bands. A norming group of, say, 200 people at one age will contain on average less than one person at 145 or above. Scores out there are extrapolated, not observed.
- Ceiling effects. On their standard norms, the composite scores of the WAIS and Stanford-Binet top out around 160; extended norms used in gifted assessment go higher, with even less precision. Someone who answers nearly everything correctly hits the ceiling, and the test cannot tell how far above it they are.
- Measurement error. Every score carries error of several points. At the top of the scale, one or two extra correct answers can move a score by a large amount, and a retest tends to come out lower simply because extreme results partly reflect a lucky day (regression to the mean).
That is why claims of an IQ of 180 or 200 should make you skeptical. On a modern deviation scale, 200 would be more than six standard deviations above the mean, rarer than one person in a billion. Very high numbers usually come from old ratio IQ formulas, from tests with a different standard deviation, or from no test at all.
The standard deviation point catches many people out. A score of 148 on a scale with a standard deviation of 24, used by some Cattell tests, corresponds to roughly 130 on the usual 15-point scale. Always ask which scale a number is on.
What IQ is considered gifted
There is no single legal or scientific definition of giftedness in the United States. Rules are set by states and school districts, and many use several measures, such as achievement tests, teacher ratings and work samples, not just an IQ score. When an IQ threshold is used, it is commonly around 130, sometimes with a lower cut-off of about 120 to 125 for broader enrichment programs, and some districts use percentiles such as the 95th or 98th instead.
If your child has been tested for a gifted program, the school psychologist's report should explain which test was used and how the decision was made. This article is general information, not a substitute for that individual assessment.
The Mensa IQ requirement
Mensa, the best-known high-IQ society, admits people who score at or above the 98th percentile on an approved, properly supervised intelligence test. It sets the bar by percentile rather than by a single number precisely because tests use different scales. On a test with a standard deviation of 15, the 98th percentile is about 131. On the older Stanford-Binet scale with a standard deviation of 16 it is about 133, and on a Cattell scale with a standard deviation of 24 it is about 149 (Mensa itself usually quotes 148, which is exactly two standard deviations). Each of those means the same thing: the top 2 percent.
By that standard, around 1 in 50 people qualify. Mensa is a social club with an admission test, not a scientific classification, but its 98th-percentile rule is a reasonable plain-language marker for very high measured ability.
What Terman's "Termites" showed about high IQ
Starting in 1921, Terman identified about 1,500 California schoolchildren with very high Stanford-Binet scores, mostly 140 and above, and followed them for the rest of their lives. The participants became known as the Termites, and the study continued after Terman's death in 1956.
The results cut against two stereotypes. First, the children were not frail, odd or socially troubled as a group; on average they were healthier, better adjusted and far more educated than their peers, and many became successful professionals, academics and writers (Terman & Oden, 1959). Second, high IQ did not produce genius. No Termite won a Nobel Prize. Two boys who are widely reported to have been tested as children but not selected, William Shockley and Luis Alvarez, later won Nobel Prizes in physics.
The study had real flaws. Children were mostly nominated by teachers, which skewed the group toward white, middle-class families, and Terman intervened in some participants' lives. Still, its lesson has held up: a very high IQ predicts good outcomes on average, but it is neither necessary nor sufficient for exceptional achievement.
A more modern study, the Study of Mathematically Precocious Youth, followed thousands of adolescents who scored in the top 1 percent or higher on reasoning tests. Even within that top 1 percent, those with higher scores were more likely to earn doctorates, patents and published papers decades later (Lubinski & Benbow, 2006). Ability differences matter at the top, but motivation, opportunity, interests and luck shape what happens with them.
Einstein, Hawking and famous IQ scores
The IQs you see attached to famous people, such as Einstein at 160 or Leonardo da Vinci at 190 or more, are almost always estimates, guesses or inventions. There is no record that Albert Einstein ever took an IQ test. Stephen Hawking reportedly said he did not know his IQ.
The historical numbers usually trace back to Catharine Cox, who worked with Terman. In 1926 she estimated childhood IQs for 301 eminent historical figures by reading biographies and comparing their recorded early accomplishments with what typical children could do at the same age (Cox, 1926). It was an ambitious exercise, but the scores depend on how much childhood detail happened to survive, they used the old mental-age approach, and they cannot be checked. Online lists of celebrity IQs are even less reliable, often repeating figures with no source at all.
The honest answer for almost any famous person is that their IQ is unknown. Their achievements are the evidence of their ability, and they tell you far more than a number would.
Is a high IQ the same as being a genius
No. IQ tests measure a broad general ability, often called the g factor, which predicts school performance and many life outcomes, and is one of several useful predictors of job performance. Creative genius also requires deep expertise built over years, original thinking, persistence and the right circumstances. Research on creativity commonly finds that IQ and creative achievement are only modestly related, and that above-average ability is helpful but far from enough.
If you are curious where you stand, a properly administered test by a licensed psychologist is the only way to get a reliable score at the high end. Online tests, including ours, are not built to distinguish between 140 and 160. Our free test gives an estimated IQ based on your position among other people who have taken it, with a deliberately wide range, and it is not a clinical or admissions measure. For more on what a score can and cannot tell you, see how accurate IQ tests are.