Highest IQ in the World: Who Has the Highest IQ Ever Recorded?

Updated 29 September 2026. About 13 minutes to read.

Who has the highest IQ in the world?

If you search for the person with the highest IQ in the world, the name you will see most often is Marilyn vos Savant. Guinness listed her under "Highest IQ" from its 1986 edition until 1989, based on a score of 228. She later became known for her "Ask Marilyn" column in Parade magazine.

That 228 comes from a Stanford-Binet test she took at the age of 10, using the 1937 edition. Her mental age was measured at about 22 years and 10 months. Dividing mental age by real age and multiplying by 100 gives roughly 228. That formula is called a ratio IQ, and it is no longer used, because it produces very high numbers for children who are far ahead of their age group. We explain why further down.

So there are really two questions hiding in "who has the highest IQ?". The first is whose claimed score is highest, and the answer is William James Sidis, with a claim of 250 to 300. The second is whose score was officially recognised, and the answer is Marilyn vos Savant. Neither number would hold up on a modern IQ test, and that is exactly why Guinness stopped keeping the record.

Top 10 highest IQs ever recorded

Here are the ten highest IQ scores most often claimed for real people, ranked by the number quoted. The last column tells you how much weight each number can bear. We have been strict: none of these scores comes from a modern, supervised, standardised adult IQ test.

Notice the pattern. Every score above 200 is either a childhood ratio IQ, a historical guess, a family claim or the result of an unofficial test. That is not a coincidence. As you will see below, no modern test can produce a score that high for an adult.

People with the highest IQ: the stories behind the numbers

William James Sidis: the 250 to 300 claim

Sidis was a genuine prodigy. He entered Harvard at 11 and lectured on four-dimensional bodies to the Harvard Mathematical Club while still a boy. His famous IQ of 250 to 300, however, has one source: his sister Helena, whose claim appeared in Abraham Sperling's 1946 book Psychology for the Millions. There is no record of Sidis ever sitting an IQ test that produced such a number. He later withdrew from public life, took modest clerical jobs and died at 46. His story is often told as a warning about the pressure placed on gifted children.

Marilyn vos Savant: 228 and 186

Her 228 is the most famous IQ number in the world. Besides the childhood ratio score, she is also reported to have scored 186 as an adult on the Mega Test, a high-range test that is not standardised. Vos Savant herself has said that IQ tests measure only some mental abilities and has not made her score the centre of her public life. If you want to see how a ratio score is worked out step by step, our guide on how IQ is calculated covers both the old and the modern formulas.

Terence Tao: the mathematician

Tao is one of the best-known mathematicians alive. He scored 760 on the SAT mathematics section at the age of 8, became the youngest ever gold medallist at the International Mathematical Olympiad at 13, and won the Fields Medal in 2006. The 220 to 230 figure is linked to reports on his testing as a young child. It has never been confirmed by a published adult score, and Tao does not promote any IQ number.

Kim Ung-yong: the Korean prodigy

Kim reportedly read several languages as a small child and has said he worked with NASA in his teens. Guinness once listed his IQ at 210, from tests he took at a very young age. As an adult he chose a quieter career in civil engineering and has said he does not like being called a genius.

Christopher Langan: "the smartest man in America"

Langan became famous in 1999 when American television described him as the smartest man in America. His quoted 195 to 210 comes largely from the Mega Test, a very hard puzzle test published in a magazine and completed at home. A neuropsychologist who tested him for the programme described his result as off the charts, but no exact standardised score was published.

YoungHoon Kim: the 276 claim

YoungHoon Kim has promoted a score of 276, the highest number on this list claimed by a living person. It comes from high-range tests created by IQ societies, which are usually taken online without supervision and are not normed against a representative sample of the population. No mainstream psychologist would treat such a score as comparable to a result from a clinical test like the WAIS.

Why Guinness stopped naming the highest IQ

Guinness dropped its "Highest IQ" category in 1990. The reason was simple: IQ tests are not precise enough at the very top of the scale to crown one person. Three problems make extreme scores unreliable.

• Different tests give different numbers. The same person can score 150 on one test and 170 on another, especially at the extremes, where each test has only a handful of very hard questions.
• Tests run out of questions. Once someone answers almost everything correctly, the test can no longer separate them from people who are brighter still. This is called a ceiling effect.
• There are not enough people to compare with. An IQ score tells you how you rank against a large sample of people your age. To score someone reliably at 200, you would need a comparison group much bigger than the population of Earth.

These are the same reasons we explain in our guide to whether online IQ tests are accurate: every test has a margin of error, and that margin grows as scores move away from the average.

Ratio IQ vs deviation IQ: why childhood scores look so high

Most of the headline numbers above were produced by the ratio IQ formula used in early tests:

The problem is that ratio IQ has no natural limit, and the spread of scores gets wider for gifted children. A 6-year-old reading like a 13-year-old scores over 200, even though nobody would describe that child as more than twice as intelligent as their classmates. The formula also breaks down for adults, because mental age stops rising in the late teens.

Modern tests use a deviation IQ instead. Your score shows how far you sit from the average of people your age, with 100 as the mean and 15 points as one standard deviation. On this scale, the same childhood performance would usually translate into a far lower number. This is why a ratio score of 228 and a modern score of 228 are not the same thing, and why a modern score of 228 has never been recorded.

How rare would these IQ scores be?

Because deviation IQ follows the bell curve, we can work out how rare each score would be in theory. With about 8.2 billion people alive, the numbers become striking very quickly:

In other words, if IQ follows a perfect bell curve, you would expect only about eight people alive with an IQ of 190, and probably nobody at 200. A deviation IQ of 300 is not just unlikely. It is statistically meaningless. Real-world scores do not follow the bell curve perfectly at the far ends, so treat these as theoretical figures rather than head counts. For every score from 55 to 160, see our full IQ percentile chart.

What is the highest IQ possible?

There is no fixed upper limit written into the idea of IQ, but in practice there is a clear ceiling set by the tests themselves:

• About 160 for adults. The Wechsler Adult Intelligence Scale, the most widely used clinical IQ test, reports full-scale scores up to about 160. That is four standard deviations above average, or roughly 1 in 31,500 people.
• Up to 210 for some children. In 2019 Pearson published extended norms for the WISC-V children's test, which let psychologists report scores up to 210 for exceptionally gifted children who hit the ceiling of the standard test. These are rare, specialist assessments.
• No limit for ratio IQ. The old ratio formula can produce any number, which is how the historical scores of 228 and above came about.

So the realistic answer to "what is the highest IQ possible?" is about 160 on a standard adult test. Anything above that is either an extended children's score, an old ratio score, or a claim that cannot be checked. Our guide to gifted IQ levels explains how psychologists describe scores from 130 to 180 and beyond.

Famous people and their IQ myths

Lists of the highest IQs often include famous names with very precise scores. Most of these numbers are invented.

Albert Einstein

Einstein's IQ is usually quoted as 160, but he never took an IQ test. Modern intelligence tests were still being developed when he was at school, and there is no record of him sitting one later in life. The number is a guess. Read our full article on what Einstein's IQ really was.

Stephen Hawking

Hawking is also often given an IQ of 160, but he never published a score. When The New York Times Magazine asked him about his IQ in 2004, he replied that he had no idea and that people who boast about their IQ are losers.

Elon Musk

Figures of around 155 appear on many websites. There is no evidence that Musk has taken a standardised IQ test or published a result, so any number is speculation.

Garry Kasparov: a rare real example

The chess champion is often credited with an IQ of 190. In fact, he is one of the few famous people who were actually tested. In 1987 the German magazine Der Spiegel arranged a set of tests in Baku. He scored 135 on a battery designed by the psychologist Hans Eysenck and 123 on Raven's Advanced Progressive Matrices. Those are high scores, but they are a long way from 190. It is a good reminder that world-class ability in one field does not require a record-breaking IQ.

Highest IQs in history

What about historical figures such as Leonardo da Vinci, Isaac Newton or Goethe? Nobody tested them, of course. The estimates you see usually trace back to Catharine Cox, a researcher who worked with Lewis Terman at Stanford. In 1926 she estimated the childhood IQs of 301 eminent people by studying their biographies and early achievements. Goethe received one of her highest estimates, around 210, while other famous names such as Newton and Leonardo scored well below that in her study.

Cox's estimates are an interesting piece of history, but they depend on how much was written about each person's childhood. Someone with a well-documented early life could receive a higher estimate than an equally able person whose childhood went unrecorded. Treat any historical IQ as an educated guess, not a measurement.

Does the highest IQ mean the most success?

Not necessarily. Lewis Terman's famous study of gifted children, which began in 1921, followed more than 1,500 young people with high IQs through their lives. Many did well, but the study also excluded two boys who later won the Nobel Prize in Physics, William Shockley and Luis Alvarez, because their test scores were not high enough to qualify.

The stories of Sidis and Langan point the same way. A very high IQ can open doors, but motivation, opportunity, health, personality and luck matter a great deal. IQ predicts some outcomes on average, such as school results, as our look at average IQ by profession shows, yet it tells you surprisingly little about any one person's life.

Frequently asked questions

Scores quoted for named people are reported claims and estimates, not results verified by IQScore. IQScore tests and guides are for education and entertainment and are not a clinical assessment.