Myths and famous claims
What is the highest IQ ever recorded?
What is documented
There is no verified highest IQ ever recorded. Guinness retired its highest-IQ category in 1990, saying intelligence tests were not uniform or reliable enough to name a single record holder. Modern tests such as the WISC-V and Stanford-Binet 5 report full-scale scores only up to 160.
Want your own number? The test is 25 visual puzzles, about 12 minutes, no sign-up.
The record category was retired
For years, record books listed a person with the highest IQ. In 1990 Guinness "rested" that category, saying it was no longer satisfied that intelligence tests were uniform or reliable enough to name a single record holder (Knight, Financial Times 2009). That decision is the clearest answer to the question: the organization best known for records concluded that this one could not be kept fairly. We do not name past record holders here.
Why a single record cannot work
An IQ is not a raw count like a sprint time. It is a position compared with a norm group, and three things make extreme comparisons unstable.
- Ceilings. The WISC-V full-scale IQ ranges from 40 to 160 (Pearson: WISC-V UK sample report), and the Stanford-Binet 5 composite also from 40 to 160 (PRO-ED: SB5). A clinical test simply does not report higher.
- Different formulas. Early IQ was mental age divided by chronological age, times 100 (Britannica, IQ). Under that formula, a 6-year-old performing like an average 12-year-old scores 200. Those ratio scores cannot be compared with today's deviation scores.
- Measurement error. Every score carries error. Clinical manuals report a confidence interval of around plus or minus 5 points at 95% (Wechsler, 2008), so two people a few points apart at the far edge cannot be told apart with confidence.
Try one · Quantitative Reasoning
Which number comes next?
16, 25, 36, 49, 64, ?
Tap the option you think is right, or show the answer.
Show the answer
The next number is 81 (option 2).
How to solve it
- The gaps (9, 11, 13, 15) grow by 2 each time, which is the pattern of square numbers.
- Each number is a square number: 4 × 4, 5 × 5, 6 × 6, 7 × 7, 8 × 8.
- So the next number is 9 × 9 = 81.
That was 1 puzzle. The full test has 25.
Where the giant numbers come from
Most of the highest numbers you see online are not test results at all. Catharine Cox's 1926 study gave Goethe a raw estimate of 200 for ages 17 to 26, from biographical records (Cox 1926). Published claims for Einstein run from 150 to 207 with no test behind any of them (Warne 2023). The figure of 250 to 300 often quoted for William James Sidis is a later estimate that the Straight Dope column called conjectural (Straight Dope, Sidis). A number above the range real tests report is a strong sign you are reading an estimate, a ratio score or a guess.
How rare high scores are on the curve
| IQ (mean 100, SD 15) | Higher than about | Roughly 1 in |
|---|---|---|
| 130 | 97.7% | 44 |
| 145 | 99.87% | 740 |
| 160 | 99.997% | 32,000 |
These figures follow from the normal curve. Mensa, for comparison, takes people at or above the 98th percentile on an approved supervised test (Mensa International), roughly 130 on this scale. You can explore the top of the range on the IQ 160 page or with the percentile calculator.
How to judge a record claim
- Is a specific test named, with its norms and the age at testing?
- Is the score inside the range that test can report?
- Is it a modern deviation score, an old ratio score or an estimate?
- Is there a primary record, or only lists that repeat each other?
For the scale limits in detail, see the highest possible IQ score. For the best-known record legend, read about William James Sidis, and for how historical numbers were made, see historical IQ estimates.
Sources
- Knight, S. (2009, April 10). Is a high IQ a burden as much as a blessing? Financial Times (read via Wayback Machine) www.ft.com/cms/s/0/4add9230-23d5-11de-996a-00144feabdc0.html
- Pearson Clinical UK. WISC-V UK sample interpretive report (Q-global). 2016. www.pearsonclinical.co.uk/content/dam/school/global/clinical/uk-clinical/files/wisc5-sample-interpretive-report.pdf
- Roid, G. H. Stanford-Binet Intelligence Scales, Fifth Edition (SB5), PRO-ED product page. 2003. proedinc.com/products-13290.html
- Encyclopaedia Britannica. IQ, revised by Jeannette L. Nolen (read via Wayback Machine, December 2024) www.britannica.com/science/IQ
- Cox, C. M. (1926). Genetic Studies of Genius, Vol. II: The Early Mental Traits of Three Hundred Geniuses. Stanford University Press (scan of original) gwern.net/doc/iq/high/1926-cox-theearlymentaltraitsof300geniuses.pdf
- Warne, R. T. (2023, September 14). The search for Albert Einstein's IQ. russellwarne.com (blog of a research psychologist) russellwarne.com/2023/09/14/the-search-for-albert-einsteins-iq/
- Adams, C. Why did William Sidis, the world's (2nd) smartest human, achieve so little in life? The Straight Dope (syndicated newspaper column; date not shown on page) www.straightdope.com/21342513/why-did-william-sidis-the-world-s-2nd-smartest-human-achieve-so-little-in-life
- About us. Mensa International. www.mensa.org/mensa/about-us
- Wechsler, D. (2008). WAIS-IV Technical and Interpretive Manual. Pearson.