IQ 165

A 165 is 5 points past the ceiling most major tests publish. The model rarity, about 1 in 136,000, describes about 60,000 people worldwide, which is far beyond anything a test has been checked against.

Real populations may not follow the bell curve perfectly in the far tails, so rarity figures this extreme are illustrations, not head counts.

Some tests publish extended norms above 160 for exceptional children. These rest on very small samples and on modelling, so they are best treated as rough rankings.

Most very high numbers you see online come from one of a few sources, and knowing which one produced a 165 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 9.9-year-old got a ratio IQ of 165. 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.

Isaac Newton and Leonardo da Vinci are usually given estimates of 160 or more, and they are among 42 such profiles here. Only 20 go as high as 165. 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.

Scoring 165 or higher is a 0.00073% share of everyone. Scaled up to whole populations, that works out as:

Going from 160 to 165 makes a score 4.3 times rarer, and going on to 170 multiplies the rarity by another 4.8. Near 165, each single point adds about 36% to the rarity.

What your 165 could really be. At this height the margin of error is wide. Just 5 points either way, 160 or 170, changes the model rarity from 1 in 31,600 to 1 in 653,000, which shows how fragile such numbers are.

Which scale was it on? Score reports do not always say. On the common SD 15 scale your 165 stands as it is. If the report used SD 16 it equals about 161, and if it used SD 24 about 141. The percentile follows the converted number.

Estimates this high are reserved for a small group of scientists, artists and thinkers. These sit near 165. Treat these as informed guesses from biographies rather than results. Each profile sets out what its estimate rests on.

Nearby scores and the round-number landmarks, so you can see how quickly the percentile changes around 165. Every row links to that score's page.