Isaac NewtonPhysicist and mathematician
Cox rated him 170 for ages 17 to 26, 1 point below 171. Cox's childhood rating for him was 130.
IQ 171: almost one in a million
An IQ of 171 is higher than about 99.99988% of people, roughly 1 in 905,541, which makes it the closest whole score to one in a million. That is the level the Mega Society asks for, and the story of how people have tried to prove it says a lot about the limits of IQ tests.
99.99988thpercentile
1 in 905,541score 171 or higher
Exceptionally giftedlevel of giftedness
171IQ scoreTop 0.00011%
Where 171 sits on the bell curve
An IQ of 171 is 71 points above the average of 100, or 4.73 standard deviations. That is so far into the right-hand tail of the bell curve that the people scoring this high barely show up: about 0.00011% of the population, the orange sliver below.
Exactly one in a million falls between 171 and 172 on the standard scale: 171 is the last whole score below that line.
A closer look at an IQ of 171
No standard clinical test can confirm a 171: the WAIS-IV and Stanford-Binet 5 stop at 160, and extended scales are built for children. So the Mega Society, founded in 1982 by Ronald Hoeflin, has relied on unusual "high-range" tests, long, hard puzzles taken at home without a time limit, which it says must be "credibly claimed to be able to discriminate" at the one-in-a-million level.
Worldwide, the bell curve predicts about 9,000 people at 171 or above. The Guinness Book of World Records once described the Mega Society as the most elite high-IQ society, with 26 members. Even if every one of the world's 9,000 had taken a high-range test, the tests themselves would struggle to tell them apart.
How many people have an IQ of 171?
On the bell curve, about 1 person in 905,541 scores 171 or higher. The animation builds a crowd until you would expect to find one.
A crowd of 905,541 people
905,541
Each dot is one person. In a crowd this size, on average, just one would score 171 or above: the orange dot.
People scoring 171 or higher, by population
| Worldwide (8.2 billion people) | about 9,070 |
| India | about 1,620 |
| United States | about 377 |
| United Kingdom | about 77 |
| Canada | about 46 |
| Australia | about 30 |
Population: World Bank, total population, 2025. Counts assume the same bell curve in every country and are rounded. Real tests can't sort people this finely, as the next sections explain.
Which high-IQ societies accept an IQ of 171?
High-IQ societies set entry as a percentile, then print the matching score for each test they accept. A supervised 171 would meet every one of these bars.
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MensaTop 2% (98th percentile) on an approved, supervised test130met
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IntertelTop 1% (99th percentile); lists a Wechsler full-scale IQ of 135135met
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Triple Nine Society99.9th percentile; lists a WAIS full-scale IQ of 146146met
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International Society for Philosophical Enquiry99.9th percentile; lists a WAIS-III or WAIS-IV full-scale IQ of 146146met
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Prometheus Society1 in 30,000 (99.997th percentile), four standard deviations above average160met
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Mega SocietyOne in a million, beyond the range of standard tests171met
Scores for Mensa, Intertel, Triple Nine and ISPE are the Wechsler figures those societies list or that match their percentile. Prometheus and Mega give only a rarity; the scores shown are the matching points on the standard scale. Prometheus says no test currently being given is approved for its entry. Online test results are not accepted by any of them.
Can an IQ test measure 171?
Not on a standard clinical test. The WAIS-IV and the Stanford-Binet 5 report full-scale scores up to 160, so 171 is 11 points beyond where they stop. Only extended scales built for gifted children reach this far: the WISC-V extended norms go to 210 and the Stanford-Binet 5 Extended IQ to 225.
The deeper problem is evidence. Tests are scored against a norm sample, and for the adult Wechsler test, the WAIS-IV, that sample was 2,200 people aged 16 to 90. On the bell curve you would expect about 0.0024 of those people to score 171 or higher, a tiny fraction of one person. Extended scales get around this by using the patterns of children who hit the ceiling, but any score this high is an estimate projected from the curve.
Every score also carries measurement error, typically about five points either way, so 171 is best read as roughly 166 to 176, a range that lies entirely beyond what standard tests report. At these heights, extended-scale scores are also less certain than the margin suggests, because so few people have ever been measured there. Online tests can't reach this level at all; ours reports up to 145. How accurate are online IQ tests?
Sources: WAIS-IV range and norm sample from Canivez (2010), Mental Measurements Yearbook review; Stanford-Binet 5 and its Extended IQ from PRO-ED; WISC-V extended norms from Pearson Technical Report #6 (2019). Striped bars are extended scales, used only when a person hits the normal ceiling.
171 IQ on other scales
The same performance gives different numbers on scales with a different standard deviation, and the gap is widest at the top.
171standard scale (SD 15), used by Wechsler tests and on this page
176older Stanford-Binet scale (SD 16)
214Cattell scale (SD 24), used by some older and online tests
It works the other way too. A 171 quoted from a Cattell-scale test equals only about 144 on the standard scale, and a 171 on an SD 16 test equals about 167. How IQ standard deviations work.
Famous people with an estimated IQ near 171
No historical genius took an IQ test. These figures come from Catharine Cox's 1926 study, which estimated IQs from records of each person's early life, with one rating for childhood and one for ages 17 to 26.
Estimate, not a test
Jeremy BenthamPhilosopher
Cox rated him 170 for ages 17 to 26, 1 point below 171. Cox's childhood rating for him was 180.
Estimate, not a test
Alexander PopePoet
Cox rated him 170 for ages 17 to 26, 1 point below 171. Cox's childhood rating for him was 160.
Source: Cox, C. M. (1926), Genetic Studies of Genius, Vol. II: The Early Mental Traits of Three Hundred Geniuses, Stanford University Press. Cox stressed that thin records pull estimates down. Read more in where the historical genius IQ estimates came from.
Famous people said to have an IQ of 171: real or myth?
Lists of celebrity IQs put many famous names at or near 171. We traced each figure to its earliest source, and none comes from a published IQ test.
JP
170No evidence of a test
Judit Polgár
The strongest female chess player in history, but no record of any IQ test could be found behind the figure.
Sources for every claim are listed in our celebrity IQ list.
The Mega Test, and why it was retired
The society's profile rose in 1985, when Hoeflin's Mega Test was published in Omni magazine. People who met the entrance requirement through it include the columnist Marilyn vos Savant and the mathematician Solomon Golomb. Like other high-range tests, it was taken at home without supervision, which is part of why so many people could attempt it.
It was also its weakness. The society says the Mega Test "was also compromised, so scores after 1994 are currently not accepted", and a later test, the Titan, "was retired in 2020 due to also having been compromised". Once answers circulate, a home test can no longer separate ability from access.
Sources: Mega Society, About the Mega Society; Ronald K. Hoeflin, Wikipedia, on how the Mega Test was taken.
What does an IQ of 171 mean?
A score of 171 means a rank of about one in a million for your age. Because no supervised standard test reaches it, a claimed 171 almost always comes from an extended children's scale or an unsupervised high-range test, and it is worth asking which before reading much into it.
Where 171 falls among the levels of giftedness
115–129Mildly gifted
130–144Moderately gifted
145–159Highly gifted
160–179Exceptionally gifted
180+Profoundly gifted
Levels and ranges from Gross, M. U. M. (2000), "Exceptionally and Profoundly Gifted Students: An Underserved Population", Understanding Our Gifted. They are a guide for education, not a ranking of people.
How far 171 is from other milestones
25 points above the Triple Nine and ISPE bar (146)a score of 171 is about 980 times rarer than 146
11 points above the ceiling of most professional tests (160)a score of 171 is about 29 times rarer than 160
Exactly at the Mega Society's one-in-a-million levelabout one in a million, the Mega Society's entry level
9 points below the start of the profoundly gifted band (180)reaching 180 is about 23 times rarer than 171
4.73 standard deviations above averageaverage is 100 and one standard deviation is 15 points
IQ 171 compared with nearby scores
| IQ | Percentile | Rarity | Level |
|---|---|---|---|
| 167 | 99.9996th | 1 in 251,738 | Exceptionally gifted |
| 169 | 99.99978th | 1 in 473,383 | Exceptionally gifted |
| 171 | 99.99988th | 1 in 905,541 | Exceptionally gifted |
| 173 | 99.999943rd | 1 in 1,762,173 | Exceptionally gifted |
| 175 | 99.999971st | 1 in 3,488,556 | Exceptionally gifted |
Questions about an IQ of 171
Is 171 a high IQ?
Yes. 171 is a very high IQ: about 1 person in 905,541 scores this high or higher, which puts it at the 99.99988th percentile. It is above the 130 that most definitions use for a high IQ, and at or above the 146 used by the Triple Nine Society for its 99.9th percentile entry.
How rare is an IQ of 171?
About 1 person in 905,541 scores 171 or higher, on the standard bell curve. Across the world's population of about 8.2 billion, that would be roughly 9,070 people.
Is an IQ of 171 good?
Yes, by any measure. 171 is higher than about 100% of people. Remember that a score this high needs a supervised professional test to be confirmed, and that it describes reasoning on a test, not every kind of talent.
Can you join Mensa with an IQ of 171?
Yes. Mensa accepts the top 2% on an approved, supervised test, which is about 130 on the standard scale. A supervised 171 would also meet the bar for Intertel, Triple Nine Society, International Society for Philosophical Enquiry, Prometheus Society and Mega Society. Online test results are not accepted.
What does 171 IQ mean?
It means a result 71 points, or 4.73 standard deviations, above the average for your age. On the levels used by gifted education researchers, 171 is exceptionally gifted (160–179).
Is 171 IQ one in a million?
Very nearly. On the standard bell curve, about 1 person in 905,541 scores 171 or higher, and the exact one-in-a-million point falls between 171 and 172. That is the entry level the Mega Society uses.
Related: what counts as a good IQ score, the highest IQ in the world, famous people's IQs and the full IQ scale and range chart.
A full IQ score of 171 combines several skills. Our guides explain each one: abstract reasoning, spatial reasoning, verbal reasoning, processing speed and fluid vs crystallized intelligence, or try the free pattern recognition test.
Famous names are often linked to scores like 171, with or without a source. We checked the evidence behind Stephen Hawking's IQ, Bill Gates' IQ, Elon Musk's IQ, Garry Kasparov's IQ, Terence Tao's IQ, Einstein's IQ, Isaac Newton's IQ and Nikola Tesla's IQ.
Curious where you'd land?
The free Assessivo IQ test gives an estimated IQ and percentile in about 25 minutes. It reports scores up to 145; for anything higher, a supervised professional assessment is the only reliable route.
Take the free IQ testPortraits are pencil-style sketches by Assessivo, based on: Isaac Newton after Godfrey Kneller (1689), public domain.