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

Search for the highest IQ ever recorded and you get a parade of giant numbers: 228, 230, 250, even 300. They look precise, and they get repeated everywhere as fact. Very few of them come from a modern adult IQ test, and some come from no test at all. Here is who is actually on those lists, where each number comes from, and why “highest IQ ever” is a much harder title to award than it sounds.

Who has the highest IQ in the world right now?

Officially, no one. For a few years, Guinness World Records had a “Highest IQ” category, and then it stopped. According to PsyPost’s 2026 review of the record, Guinness removed it in 1990, saying that “intelligence tests at the extreme high end of the spectrum were too unreliable to designate a single world record holder.” Mental Floss reports the same decision: the tests were “too unreliable to warrant a single record holder.”

That reasoning still holds. A widely used adult intelligence test, the WAIS-IV, reports full-scale IQ scores only from 40 to 160, according to psychologist Gary Canivez’s review of the test for the Mental Measurements Yearbook (Canivez, 2010). Its norms rest on a sample of 2,200 people. A test like that can tell you someone is at or near the very top. It cannot rank the top few people on the planet against each other.

So the honest answer to “who has the highest IQ in the world” is that no test, ranking or record body can name one person. What you can do is sort the famous claims into three piles: measured, estimated and made up.

The highest IQ ever recorded: Marilyn vos Savant’s 228

Marilyn vos Savant is the name Guinness attached to the highest IQ ever recorded, and Mental Floss notes she held the listing from 1986 to 1989. The score behind it has a specific history.

According to PsyPost, vos Savant took the Stanford-Binet in 1956, at age 10, and the test put her mental age at 22 years and 10 months. In that era, IQ was a simple ratio: mental age divided by actual age, times 100. So 22.83 ÷ 10 × 100 ≈ 228.

That formula was built for children, and it inflates scores at the extremes. A 10-year-old who solves problems like a young adult earns a huge ratio, but that tells you little about how rare her ability is compared with other 10-year-olds. Psychologist Andrew Colman, writing in The Skeptic, calculated that 228 would sit 8.53 standard deviations above the mean on a modern scale, with odds of less than 1 in 100 quadrillion, and argued that a valid score of 228 on today’s scale is effectively impossible (via PsyPost).

As an adult, vos Savant took a different test, the high-range Mega Test, in the mid-1980s and scored 186. Same person, two tests, a 42-point gap. That gap is a good summary of why Guinness gave up on the category.

If you want the full story of how IQ went from that ratio to the modern deviation score, our guide to what IQ is and how it is calculated walks through both formulas with examples.

The highest IQ of all time? The names on every list

Most “highest IQ of all time” lists recycle the same handful of people. All of them are genuinely remarkable. The question is only whether the numbers attached to them hold up.

Terence Tao: claimed 230

The Australian-born mathematician Terence Tao (born 1975) usually sits at the top. His record is real: according to the National Portrait Gallery of Australia, he began studying math at Flinders University at age 9, won bronze, silver and gold medals at the International Mathematical Olympiad at ages 10, 11 and 12, and finished his PhD at Princeton at 21. He has been a full professor at UCLA since 2000, and the International Mathematical Union awarded him the 2006 Fields Medal.

The 230, however, is not a test score. According to PsyPost, Tao scored 760 out of 800 on the SAT math section at age 8, and researchers Julian Stanley and Miraca Gross used that result to estimate an IQ between 220 and 230. That figure is an extrapolation from a childhood admissions test, not a published IQ test report. According to the same report, Tao himself has called the measurement “extremely noisy at these scales” and suggested that an IQ “greater than 175” is a more realistic estimate.

William James Sidis: claimed 250 to 300

Sidis (1898 to 1944) is the classic “smartest man who ever lived” story. NPR’s 2011 profile reports that Harvard accepted him at 9 but asked him to wait until 11, that he graduated cum laude five years later, and that by age 6 he reportedly knew eight languages, including Latin, Russian, Hebrew and Turkish.

The 250 to 300 range is the weakest number on this page. It traces back to psychologist Abraham Sperling’s chapter “A Story of Genius” in the 1946 book Psychology for the Millions (online transcription). Sperling wrote that Sidis’s sister Helena told him her brother had taken an intelligence test a few years before his death, and that “the psychologist related that the figure would be between 250 and 300.” No test name, no date, no examiner and no record. NPR’s own wording is that his IQ was “estimated” to be 50 to 100 points higher than Einstein’s (a comparison with a score Einstein never had).

Kim Ung-yong: claimed 210

Born in Seoul in 1962, Kim Ung-yong was famous across Asia as a toddler. A 2014 profile in the Korean daily Joongboo Ilbo reports that a Japanese institution measured his IQ at 210 when he was a child, and The Korea Herald notes that Guinness once listed him as having the world’s highest IQ. The Herald adds that the media later branded him a “failed genius.” He studied civil engineering at Chungbuk National University and in 2014 became a full-time professor at Shinhan University, and he has maintained that he has led a happy life. His 210 is, again, a childhood figure, with no published test report behind it.

Christopher Hirata: claimed 225

American astrophysicist Christopher Hirata became the youngest American to win a gold medal at the International Physics Olympiad, at 13, according to The Daily Princetonian. Princeton Alumni Weekly reports he started at Caltech at 14 and was a Princeton PhD student at 18. He went on to win the 2018 New Horizons in Physics Prize as an Ohio State professor.

The “225” attached to his name has no visible source. The Daily Princetonian, writing in 2017, said only that his IQ “has been stated to be around 225,” in a story about a web “top 10 most intelligent people” list. Nobody says who measured it, or how.

Christopher Langan: claimed 195 to 210

Christopher Langan became “the smartest man in America” through a late-1990s Esquire profile, which, as quoted by The Baffler (Justin Ward, 2019), described his IQ as “measured at 195, give or take a few points.” His reputation rests largely on the Mega Test, a high-range test designed by Ronald Hoeflin that was taken by mail, untimed and unsupervised, according to NZ Skeptics. The same article quotes Langan estimating his own IQ as “somewhere between 190 and 210.” No published test report backs any of these numbers.

Highest IQ claims vs. what is actually documented

Put the famous names side by side and a pattern jumps out: the bigger the number, the thinner the evidence.

Einstein, Stephen Hawking and Elon Musk also show up on these lists, usually at 155 to 160. None of them has a published test score either. We cover those separately in Einstein’s IQ: the 160 myth and our breakdown of famous people’s IQ scores.

The rare case of a champion tested as an adult: Garry Kasparov

The most useful entry in that table is the least flashy. In 1987 the German magazine Der Spiegel sent a team to Baku to test Garry Kasparov, then the 24-year-old world chess champion, over three days. The December 20, 1987 article reports that he scored 135 on a test psychologist Hans Eysenck assembled for the occasion and 123 on Raven’s matrices.

Both results are well above average. On a normal curve with mean 100 and standard deviation 15, an IQ of 135 is higher than about 99% of people. Der Spiegel drew the sensible conclusion at the time: an IQ can be no more than a rough indicator, as his two results in Baku already showed. By our count, they sit 12 points apart.

That is what real measurement looks like. Two tests, the same person, the same week, different numbers, and none of them in the 200s.

How high can an IQ go? Why 200 and up breaks down

A modern IQ is a ranking on the IQ scale: it says where you stand compared with a large group of people your age. Because scores follow a bell curve, you can compute how rare each score should be. Here is what the famous numbers imply.

The United Nations reports that the world’s population reached 8 billion on November 15, 2022. On the standard scale, a score of 200 would be expected in roughly one person among nearly ten Earths’ worth of people. There is simply no reference group big enough to confirm a score like that, which is why a test such as the WAIS-IV stops at 160.

That is the second problem: test ceilings. A test can only distinguish people where it has enough hard questions and enough comparison data. At the top of the scale both run out. Every number above about 160 in the table you saw earlier comes from an old childhood ratio score, a special high-range test or an estimate. For how percentiles and rarity work across the whole curve, see our IQ bell curve and percentiles guide; for where the “genius” label starts, read what IQ is considered genius.

How to check any “highest IQ ever” claim

Next time a list tells you someone has an IQ of 210, run it through four questions:

1. Who measured it, and with which test? A named, standardized test given by a qualified examiner is a measurement. “It has been stated” is not.
2. How old was the person? Childhood scores from the ratio era are not comparable with adult deviation scores.
3. Was it supervised and timed? Take-home, untimed tests measure something different from a standard clinical session.
4. Is the score inside the test’s range? If a test reports up to 160, a claim of 230 is not a measurement.

Does the highest IQ make the smartest person in the world?

Look again at what actually makes these names famous. Tao has a Fields Medal. Hirata has a major physics prize. Kasparov was world champion. The evidence of their ability is in what they did, not in a three-digit number.

IQ tests measure real and useful abilities: pattern finding, reasoning, working memory, processing speed (our evidence check on signs of a high IQ covers which everyday traits really go with them). But persistence, curiosity, training and years of focused work do not fit on a score report. Kasparov’s case makes the point neatly: a measured 123 to 135 belonged to one of the strongest chess players who ever lived. Sidis, the man with the biggest number of all, spent much of his adult life avoiding public attention, moving from job to job, often under an alias, according to NPR.

So the best answer to “who is the smartest person in the world” is that the question is too big for one number, and the record books agree.

Where does your own score fall?

The famous numbers are mostly estimates. Yours does not have to be. A measured score, even an unspectacular one, tells you more than any celebrity guess: it shows where you stand on the same mean-100 scale used throughout this article, and which kinds of thinking come easiest to you.

When you take the IQtonics IQ test, you answer 40 questions across five areas (patterns, spatial reasoning, numbers, logic and memory) within a 20-minute time limit. Questions get harder as you go, and harder ones carry more points. Your result comes as a standard IQ score with a percentile, plus a profile of your strongest and weakest areas. Starting the test is free; your full results unlock with a trial membership, which renews automatically unless you cancel it.

One honest caveat: it is an online test, not a clinical assessment. If you want to know how online tests compare with the ones psychologists use, read are online IQ tests accurate? before you start.