IQ scores
What an IQ of 90 means
An IQ of 90 is at the 25 percentile on the standard scale. About 1 person in 4 scores this low or lower. It falls in the range usually labelled average.
IQ 90 at a glance
| Percentile | 25 |
| Rarity | 1 in 4 (this low or lower) |
| Range | Average (about 50 in 100 of people) |
| Distance from average | 0.67 standard deviations below |
| Same result on SD 16 | 89 |
| Same result on SD 24 (Cattell) | 84 |
What it tells you
A score of 90 is in the average range, where half of all adults fall. Differences of a few points here are smaller than the margin of error of any test, so 90 and 95 are not meaningfully different results.
Most people in every occupation score in this range. Within it, things a test does not measure, such as persistence, knowledge and practice, matter far more than the number.
How sure can you be of a score of 90?
That depends on the test. On a long, supervised assessment the margin of error is a few points. On a short online test it is around ten, so a reported 90 means a true score probably somewhere between 79 and 101. That span runs from the 8 to the 53 percentile.
Scores also depend on the scale. If your 90 came from a test using a standard deviation of 16 or 24, it is not the same as 90 here; the percentile calculator converts between them.
Nearby scores
- IQ 85: 16 percentile.
- IQ 95: 37 percentile.
- The full IQ scale, with every range.