Prepared by IQInsight · Updated
Where the “genius IQ” of 140 comes from.
In 1916 Lewis Terman published the Stanford revision of the Binet–Simon intelligence scale and suggested labels for score ranges. Scores above 140 were described as “near genius or genius”. The label stuck in popular writing long after psychologists stopped using it.
Terman’s scores were ratio IQs for children, so his 140 is not exactly today’s 140. Current manuals call 130 and above “very superior” (WAIS-IV) or “extremely high” (WISC-V). Neither has a genius category.
How rare are the usual “genius” thresholds?
| IQ | What it marks | Higher than | How common |
|---|---|---|---|
| 130 | Mensa admission level, the top 2% | 97.72% | 1 in 44 |
| 140 | Terman’s 1916 “near genius or genius” line | 99.62% | 1 in 261 |
| 145 | Three standard deviations above the mean, near the top 0.1% used by the Triple Nine Society | 99.87% | 1 in 741 |
| 160 | Highest full-scale score on the WAIS-IV and WISC-V | 99.997% | 1 in 31,574 |
Every 15 points cuts the share of people sharply. Above 145 the numbers are so small that a test needs a very large norm sample to tell one score from the next.
Why scores above 145 are hard to trust.
Few people in any norm sample score at the very top, so the difference between 150 and 160 rests on a handful of answers. Major tests stop at 160. Claims of 190, 200 or more usually come from childhood ratio IQs, mental age divided by actual age, or from extrapolating beyond the norms, and cannot be compared with modern scores.
The same caution applies to famous names. Most “IQ scores” quoted for historical figures are estimates made long after their lives, not test results.
What Terman’s own study found.
Terman followed about 1,500 children with very high scores for decades. As a group they did well, with more degrees and more professional careers than average. Yet two boys who were tested and not selected, William Shockley and Luis Alvarez, later won Nobel Prizes in physics. None of the selected children did.
Exceptional achievement takes more than a high score: years of work in a field, opportunity, creativity and some luck.
So which number should you use?
If you need a working definition, 130, about the top 2.3%, is the level used by Mensa and many gifted programmes, and 140 is the traditional “genius” figure. Both describe how rare a test performance is, and nothing more. For the full picture, see what is a high IQ and IQ score ranges & chart.