IQ 198
Profoundly Gifted
Quick answer
Yes, and it is extremely rare. An IQ of 198 is higher than all but about 1 in 31 billion people.
Most tests cannot measure this high reliably, so read a 198 as "far above 150" rather than an exact number. The rarity comes from the bell curve model.
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Where 198 falls on the bell curve
198 is plotted on a curve stretched to 200. The tail to its right is real but far too thin to see, which is the visual version of 1 in 31 billion.
IQ 198: beyond what most tests can measure
198 is 6.53 standard deviations above the mean. On a bell curve that works out to about 1 in 31 billion people, which is fewer than one person in the entire world population. The bell curve is a model, though, and at this height it is doing most of the work.
Real populations may not follow the bell curve perfectly in the far tails, so rarity figures this extreme are illustrations, not head counts.
None of this means nobody is this able. It means a single number is not a reliable way to describe them.
How claims like "198 IQ" arise
Most very high numbers you see online come from one of a few sources, and knowing which one produced a 198 tells you how much weight to put on it.
- Ratio IQ. Early childhood tests divided mental age by real age. A 6-year-old solving puzzles like a typical 11.9-year-old got a ratio IQ of 198. Modern deviation IQs do not work this way.
- Historiometric estimates. Researchers such as Catharine Cox (1926) estimated IQs for famous people from biographies. Some of her adjusted estimates went above 200. They are educated guesses, not test results.
- Repetition without a source. Numbers attached to celebrities are often copied from site to site with no test report behind them.
Famous estimates: Newton, da Vinci and the 160+ club
Isaac Newton and Leonardo da Vinci are usually given estimates of 160 or more, and they are among 37 such profiles here. No estimate on this site goes as high as 198. All are judgements from biographies, not test results.
Estimates this high mostly reflect how extraordinary the achievement was. That is a different thing from how someone would perform on a timed reasoning test.
How many people have an IQ of 198 or higher?
Scoring 198 or higher is a 0.0000000032% share of everyone. Scaled up to whole populations, that works out as:
| Where | Population | IQ 198 or higher |
|---|---|---|
| UK | about 68 million | fewer than one (effectively zero expected) |
| US | about 335 million | fewer than one (0.01 expected) |
| World | about 8.1 billion | fewer than one (0.26 expected) |
Even across the whole world of 8.1 billion people, the bell curve predicts fewer than one person at 198 or higher.
About 1 in 69 billion people would score exactly 198, meaning between 197.5 and 198.5 on a continuous scale. In the UK that is fewer than one person.
These are model estimates: a bell curve applied to whole populations, including children, rounded. They are not census counts, and real test norms differ a little from one test to another.
How rare is an IQ of 198?
Going from 193 to 198 makes a score 8.8 times rarer, and going on to 203 multiplies the rarity by another 9.8. Near 198, each single point adds about 56% to the rarity.
What your 198 could really be. No test is precise this far out. Even a 5-point error band, from 193 to 203, spans a rarity gap of about 86 times, so the exact number matters much less than "very far above average".
Which scale was it on? Score reports do not always say. On the common SD 15 scale your 198 stands as it is. If the report used SD 16 it equals about 192, and if it used SD 24 about 161. The percentile follows the converted number.
Famous people with an estimated IQ near 198
Estimates this high are reserved for a small group of scientists, artists and thinkers. These are the closest to 198. Treat these as informed guesses from biographies rather than results. Each profile sets out what its estimate rests on.
Fictional characters near 198
For fun, not science: fan estimates for the characters nearest 198, based on how they reason in their stories.
198 compared with nearby scores
How 198 stacks up against the scores just around it and the round numbers people usually ask about. Each score links to its own page.
| IQ | Classification | Percentile | Score higher |
|---|---|---|---|
| IQ 10098 lower | Average | 50th | 50% |
| IQ 11088 lower | High Average | 74.8th | 25% |
| IQ 12078 lower | Superior | 90.9th | 9.1% |
| IQ 13068 lower | Gifted | 97.7th | 2.3% |
| IQ 14058 lower | Gifted | 99.62nd | 0.38% |
| IQ 15048 lower | Genius | 99.96th | 0.043% |
| IQ 1935 lower | Profoundly Gifted | 99.999999971st | 0.000000028% |
| IQ 1971 lower | Profoundly Gifted | 99.9999999949th | 0.000000005% |
| IQ 1991 higher | Profoundly Gifted | 99.9999999979th | 0.0000000021% |
Is 198 a good IQ?
Yes, in the sense that it is extraordinarily high: about 1 in 31 billion on the bell curve, 38 points past the ceiling of most major tests. The catch is precision. A single 198 is better treated as "well above 150" than as an exact score.
What percentile is an IQ of 198?
On the standard scale, 198 lands at about the 99.9999999967th percentile: only 0.0000000032% of people match or beat it. Percentiles depend on the scale, so check that your score report uses a standard deviation of 15 before comparing it with this page.
Is 198 genius level?
By most informal definitions, yes. There is no clinical genius category, but scores above 140 or 145 are often labelled that way, and 198 is well past both. Historically, though, genius is defined by achievement, and no test measures this high precisely.
What does an IQ of 198 mean?
It means you scored 6.53 standard deviations above average on the kind of reasoning an IQ test samples, which this site classes as Profoundly Gifted. Most tests cannot measure this high precisely. It measures reasoning on that test, not knowledge, creativity or character.
How rare is an IQ of 198?
198 or higher happens in about 1 in 31 billion people. In the UK that is fewer than one person. Scoring exactly 198, meaning 197.5 to 198.5 on a continuous scale, is about 1 in 69 billion. Both figures come from the standard bell curve, not a census.
What is the mental age for an IQ of 198?
Mental age is a childhood measure. On the old ratio scale, a 12-year-old with an IQ of 198 performed like a typical 23.8-year-old. For adults the idea breaks down, because reasoning scores stop rising with age, so modern tests compare you with people of your own age.