IQ 163

Taken literally, the bell curve puts 163 at 1 in 74,900: about 910 people in the UK and about 110,000 people worldwide. Treat that as an illustration of the model rather than a head count.

No test has enough people in its norm sample to check its accuracy at 163. In a 2,200-person sample the bell curve expects about 0.03 people at 163 or higher.

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

If someone tells you they have a 163, the first question is where the number came from. The usual answers:

• 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.
• Unnormed online quizzes. A test with no norm data can print any number. Very high outputs usually say more about the scoring than the person.
• 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 163. All are judgements from biographies, not test results.

As far as anyone knows, Albert Einstein never took an IQ test. The 160 figure repeated online is an estimate. See the Einstein profile for what it rests on.

Scoring 163 or higher is a 0.0013% share of everyone. Scaled up to whole populations, that works out as:

Going from 158 to 163 makes a score 4.1 times rarer, and going on to 168 multiplies the rarity by another 4.6. Near 163, each single point adds about 35% to the rarity.

What your 163 could really be. Treat any single score as the centre of a range. For a good supervised test, about 5 points either side is typical, so 163 really means somewhere from 158 to 168. Online tests are less precise than that.

Which scale was it on? Score reports do not always say. On the common SD 15 scale your 163 stands as it is. If the report used SD 16 it equals about 159, and if it used SD 24 about 139. The percentile follows the converted number.

Estimates this high are reserved for a small group of scientists, artists and thinkers. These sit near 163. Treat these as informed guesses from biographies rather than results. Each profile sets out what its estimate rests on.

How 163 stacks up against the scores just around it and the round numbers people usually ask about. Each score links to its own page.