Estimate, not a test
Philip MelanchthonReformation scholar
Cox rated him 180 for ages 17 to 26, 2 points above 178. Cox's childhood rating for him was 160.
What does a 178 IQ mean?
A 178 IQ means a score higher than about 99.99999% of people: roughly 1 in 10,035,701, or almost exactly one in ten million. It is close to the 180 often given to Leonardo da Vinci, and it is the figure online lists attach to actor Rowan Atkinson, for which we could find no source at all.
99.99999thpercentile
1 in 10,035,701score 178 or higher
Exceptionally giftedlevel of giftedness
178IQ scoreTop 0.00001%
How far out on the bell curve is 178?
Plot 178 on the bell curve and it lands 5.2 standard deviations, or 78 points, to the right of the average. The area beyond it, coloured orange below, holds only 0.00001% of people, too thin to see without zooming in.
One in ten million: the bell curve predicts about 34 people this high in the United States and about 7 in the UK.
What makes 178 different
Leonardo's "180" is a good example of how a historical estimate becomes a fact. Catharine Cox's 1926 study rated him at 135 for childhood and 150 for ages 17 to 26, from records of his early life. Her later correction for incomplete records raised that to 180. The correction is an argument about missing evidence, and Leonardo never sat any test.
The Rowan Atkinson figure has an even thinner basis. It appears on countless lists of celebrity IQs, but as our famous people guide found, it has no traceable source: no interview, no test record and no published estimate.
How many people have an IQ of 178?
To meet one person scoring 178 or above, you would need, on average, a crowd of 10,035,701. Here is that crowd, built up step by step.
A crowd of 10,035,701 people
10,035,701
Every dot stands for a person. Only the orange one, one in the whole crowd, would be expected to reach 178.
People scoring 178 or higher, by population
| Worldwide (8.2 billion people) | about 819 |
| India | about 146 |
| United States | about 34 |
| United Kingdom | about 7 |
| Canada | about 4 |
| Australia | about 3 |
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 178?
Each society below admits a set top slice of the population and lists the score that matches it on the Wechsler adult scale. With a supervised result of 178, you 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 178?
A score of 178 is 18 points past the ceiling of the main clinical tests, which stop at 160. The bars show the highest full-scale result each test can give; only the extended scales, used mainly with exceptionally able children, can report 178.
Behind every score is a norm sample: for the WAIS-IV, 2,200 adults. The bell curve predicts about 0.00022 of them at 178 or above, far less than one person, so no standard test has ever compared anyone with real 178 scorers. Extended norms are built from children who reach the ceiling of the standard test, and their scores rest on that projection.
Add the usual margin of error, about five points either way, and a result of 178 really means somewhere near 173 to 183. Very few people have ever been tested this high, so even extended scales are working near the limit of their evidence. No online test can pin down a score like this, ours included. What online tests can and can't tell you.
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.
Is 178 the same on every IQ scale?
IQ tests don't all use the same yardstick. A scale with a larger standard deviation turns the same rank into a bigger number, especially this far above average.
178standard scale (SD 15), used by Wechsler tests and on this page
183older Stanford-Binet scale (SD 16)
225Cattell scale (SD 24), used by some older and online tests
Turn it around: if a test using the Cattell scale reports 178, the standard-scale equivalent is just 149. From an SD 16 test, 178 converts to about 173. Check the scale before comparing any high score. IQ standard deviations explained.
Historical figures rated at about 178
The figures below are not test scores. In 1926 the psychologist Catharine Cox rated 301 eminent people from records of their youth, giving each a childhood estimate and a second one for ages 17 to 26.
Estimate, not a test
Friedrich SchellingPhilosopher
Cox rated him 180 for ages 17 to 26, 2 points above 178. Cox's childhood rating for him was 175.
VoltaireWriter and philosopher
Cox rated him 180 for ages 17 to 26, 2 points above 178. Cox's childhood rating for him was 170.
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.
Celebrity 178 IQ claims, checked
Search for a 178 IQ and the same famous names keep appearing. Here is what we found when we followed each figure back to where it started.
RA
178No evidence of a test
Rowan Atkinson
The figure appears on many lists of celebrity IQs with no traceable source.
JW
180No evidence of a test
James Woods
Widely repeated and often credited to him, but no interview or test record could be found.
Sources for every claim are listed in our celebrity IQ list.
From 150 to 180: how Leonardo's IQ grew
Cox's raw estimates for Leonardo da Vinci were 135 and 150. Because she found that thinner records consistently produced lower estimates, she published corrected figures that adjusted for the reliability of each person's data, and Leonardo's rose to 180.
Cox herself called the correction "a crude approximation" that "indicates a point below which the true IQ probably did not fall". It was never meant to be quoted as a test score, yet the 180 now appears in countless lists, often without the word "estimate".
Sources: Cox, C. M. (1926), Genetic Studies of Genius, Vol. II, Stanford University Press; our famous people IQ guide.
What does an IQ of 178 mean?
A score of 178 means a rank of about one in ten million for your age, near the top of the "exceptionally gifted" band and just short of "profoundly gifted", which begins at 180. Like every score this high, it could only come from an extended scale or an old ratio test.
Where 178 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 178 is from other milestones
32 points above the Triple Nine and ISPE bar (146)a score of 178 is about 10,862 times rarer than 146
18 points above the ceiling of most professional tests (160)a score of 178 is about 318 times rarer than 160
7 points above the Mega Society's one-in-a-million level (171)a score of 178 is about 11 times rarer than 171
2 points below the start of the profoundly gifted band (180)reaching 180 is about 2 times rarer than 178
5.2 standard deviations above averageaverage is 100 and one standard deviation is 15 points
IQ 178 compared with nearby scores
| IQ | Percentile | Rarity | Level |
|---|---|---|---|
| 174 | 99.999959th | 1 in 2,474,083 | Exceptionally gifted |
| 176 | 99.999979th | 1 in 4,940,195 | Exceptionally gifted |
| 178 | 99.99999th | 1 in 10,035,701 | Exceptionally gifted |
| 180 | 99.9999951st | 1 in 20,741,280 | Profoundly gifted |
| 182 | 99.9999977th | 1 in 43,613,157 | Profoundly gifted |
178 IQ: common questions
Is 178 a high IQ?
Yes. 178 is a very high IQ: about 1 person in 10,035,701 scores this high or higher, which puts it at the 99.99999th 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.
Can an online IQ test show a score of 178?
Some can show the number, but very few can measure it. Our own test reports up to 145, because a short online test doesn't have enough very hard questions, or enough high scorers in its data, to separate 178 from nearby scores. A supervised Wechsler or Stanford-Binet assessment is needed to confirm it.
What is an IQ of 178 on the Cattell scale?
About 225. The Cattell scale uses a standard deviation of 24 instead of 15, so the same result gives a bigger number. Going the other way, a Cattell score of 178 is only about 149 on the standard scale.
What percentile is an IQ of 178?
An IQ of 178 is at about the 99.99999th percentile. Only about 0.00001% of people score 178 or higher.
How rare is an IQ of 178?
About 1 person in 10,035,701 scores 178 or higher, on the standard bell curve. Across the world's population of about 8.2 billion, that would be roughly 819 people.
Does Rowan Atkinson have an IQ of 178?
There is no evidence that he does. The figure appears on many celebrity IQ lists, but we could find no interview, test record or published estimate behind it.
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.
Behind a single score of 178 sit several separate abilities. Read about verbal reasoning, processing speed, fluid vs crystallized intelligence, abstract reasoning and spatial reasoning, or try the free pattern recognition test.
Curious which celebrity IQs near 178 hold up? Read the full stories of Nikola Tesla's IQ, Stephen Hawking's IQ, Bill Gates' IQ, Elon Musk's IQ, Garry Kasparov's IQ, Terence Tao's IQ, Einstein's IQ and Isaac Newton's IQ.
Curious where you'd land?
Our free test takes about 25 minutes and gives an estimated IQ with its percentile. Results go up to 145, so a score like 178 can only be confirmed by a psychologist.
Take the free IQ testPortraits are pencil-style sketches by Assessivo, based on: Voltaire after Nicolas de Largillière (about 1724–1725), public domain.