Average IQ and the IQ scale
The average IQ is 100. Everything else is about distance from that middle. Drag a score along the curve to see how rare it really is, and what percent genius that makes you.
Top 15.9%: above the middle of the curve.
Why the average is always 100
IQ is not a raw count of right answers. Test publishers give the test to a large sample that mirrors the population, then scale the results so the middle score is 100 and one standard deviation is 15 points. Your IQ is really a rank, expressed on that scale. That is why the bell curve above never moves: the test is built to produce it.
Because it is a rank, the useful numbers are percentiles. An IQ of 115 sounds only a little above 100, but it beats about 84% of people. An IQ of 130 beats about 97.7%; 145 beats about 99.87%.
What percent genius am I?
"Genius" is not a clinical term, and no test publisher uses it as a band. Popular writing tends to use it for IQs of 140 or above, which is roughly the top 0.4%. Treat it as bragging rights, not a diagnosis. Our 30-question IQ test gives you a score to drop into the slider.
The IQ scale at a glance
| IQ (SD 15) | Percentile | Roughly 1 in… | Band |
|---|---|---|---|
| 70 | 2.3% | — | Borderline |
| 85 | 15.9% | — | Low average |
| 100 | 50.0% | — | Average |
| 115 | 84.1% | 6 | High average |
| 120 | 90.9% | 11 | Superior |
| 130 | 97.7% | 44 | Very superior (gifted range) |
| 140 | 99.6% | 260 | Very superior (gifted range) |
| 145 | 99.865% | 740 | Very superior (gifted range) |
| 160 | 99.997% | 31,600 | Very superior (gifted range) |
Average IQ by age
The average is 100 at every age, because each age group is scored against its own peers. A ten-year-old with an IQ of 100 and a forty-year-old with an IQ of 100 are both exactly average for their age, even though the adult solves more problems.