IQ 172

172 is 4.80 standard deviations above the mean. On a bell curve that works out to about 1 in 1.3 million people, which would mean about 54 in the UK and about 6,400 worldwide. The bell curve is a model, though, and at this height it is doing most of the work.

No test has enough people in its norm sample to check its accuracy at 172. In a 2,200-person sample the bell curve expects effectively nobody at 172 or higher.

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 172 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 10.3-year-old got a ratio IQ of 172. 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 4 go as high as 172. All are judgements from biographies, not test results.

Two people with identical estimates can have very different evidence behind them. Each profile explains what its estimate is based on and how confident anyone can be.

If IQ follows the standard bell curve, 0.000079% of people score 172 or higher. Here is what that share means across whole populations:

Compare the neighbours: 167 or higher is about 1 in 252,000, 172 or higher is 1 in 1.3 million, and 177 or higher is 1 in 7 million. Each point up here adds roughly 40% to the rarity.

What your 172 could really be. Even a good supervised test has a margin of error of roughly 5 points either side, and far more at this height. A true score from 167 to 177 would span rarities from 1 in 252,000 to 1 in 7 million.

Which scale was it on? Most modern tests use a standard deviation of 15, which is what this page assumes. If your 172 came from a test using an SD of 16, it is about 168 on the SD 15 scale. From an SD 24 scale, used by some Cattell-style reports, it is about 145.

Estimates this high are reserved for a small group of scientists, artists and thinkers. These sit near 172. Treat these as informed guesses from biographies rather than results. Each profile sets out what its estimate rests on.

How 172 stacks up against the scores just around it and the round numbers people usually ask about. Each score links to its own page.