Is an IQ of 90 average?
Yes. An IQ of 90 is in the average range, where about half of all people score. It is a little below the exact middle of 100, but well within normal, and a perfectly good result for school, work and everyday life.
Where 90 sits on the bell curve
An IQ of 90 is 10 points below the average of 100, or 0.67 standard deviations. It is higher than about 25% of people of the same age, shown by the shaded area below. Scores in the 90s sit on the steep, crowded slope just left of the peak, so a few points here change your percentile a lot.
On other IQ scales, the same result would be about 89 on a test with a standard deviation of 16, such as older editions of the Stanford-Binet, and 84 on the Cattell scale, which uses 24. Why scales differ.
IQ 90 meaning: a closer look
Ninety is where the average range begins on the most widely used classification. It is higher than about a quarter of people, so it sits at the 25th percentile, the lower edge of the middle half of the population. Everyone from 90 to 109 is described as average, a band wide enough to hold about half of all people. In everyday terms, a score of 90 means you reason in a way that is typical for your age. School, work and daily problem-solving depend far more on knowledge, habits and practice than on the differences inside this band.
Average by one point: how Wechsler moved the line to 90
Classification tables are drawn by people, and their lines have moved. In The Measurement and Appraisal of Adult Intelligence (1958), David Wechsler printed two tables. On the older Wechsler-Bellevue scale, "average" ran from 91 to 110, so a 90 fell into the dull-normal class. On the newer WAIS, average ran from 90 to 109 and was set to hold 50% of people, with 16.1% in each of the classes either side. Wechsler stressed that his limits were "in nowise definitive" and could be altered with experience.
Current Pearson reports keep the same line. The WISC-V interpretive report states that full-scale IQ scores "ranging from 90 to 109 are typically considered average". So an IQ of 90 is average, but only just, and a 90 and an 89 differ by less than the test's own margin of error. What the table does tell you is that about half of all people are placed in the same broad group as you. The label describes where a score sits, not what a person can achieve.
Sources: Wechsler, D. (1958), The Measurement and Appraisal of Adult Intelligence (4th ed.), Williams & Wilkins, Tables 2 and 3; Pearson, "WISC-V Interpretive Report" (sample report).
What 90 looks like among real people
If you lined up 100 people of your age, about 25 would score lower than 90 and about 75 would score the same or higher. The orange dot marks your place in the line.
Most of the people you meet every day score within a few points of this.
How precise is a score of 90?
No IQ test measures to the exact point. On a professional test, a result of 90 usually comes with a likely range of about five points either way: 85 to 95. That range runs from the 16th to the 37th percentile, and it crosses from low average into average.
In the 90s a few points make a big difference to the percentile, because so many people score here. That is why a gap of a few points between two tests, or two people, usually means very little.
On the Assessivo test, 90 is the score for 14 correct answers out of 36. How our score is worked out.
So if you scored 90 once, a retest on another day could reasonably land anywhere from 85 to 95. Online tests are less precise still, so treat any online result as a rough estimate.
IQ 90 and mental age in children
Early IQ tests for children worked with a "mental age", the age whose typical performance a child matched. The IQ was that mental age divided by the child's real age, times 100. Turned around, the formula shows what a score of 90 would have meant for children of different ages: working a little behind their years.
| Real age | Mental age at IQ 90 |
|---|---|
| 5 | 4 years 6 months |
| 7 | 6 years 4 months |
| 9 | 8 years 1 month |
| 11 | 9 years 11 months |
| 13 | 11 years 8 months |
The same 90 stands for a gap of about 6 months at age 5 but 1 year 4 months at 13, because the formula scales with age. That is one reason it broke down for teenagers and adults, whose test performance stops rising every year. Today's tests compare you with people of the same age instead, so a mental age is only a way to picture a child's score, never a description of an adult.
What an IQ of 90 means for you
It is the very first score in the average band.
- You reason about as well as most people of your age, with a typical balance of speed and accuracy on new problems.
- Most courses, jobs and everyday decisions sit comfortably within this range of ability.
- Two people at 94 and 104 are closer than the numbers suggest: their likely ranges overlap.
How far 90 is from other levels
Why 90 is a milestone: The bottom edge of the average range (90 to 109).
How 90 compares with nearby scores
Want a score that isn't listed, or the share of people between two scores? Try the IQ calculator.
| IQ | Percentile | Classification | Score this high or higher |
|---|---|---|---|
| 80 | 9th | Low average | 91% |
| 85 | 16th | Low average | 84% |
| 90 | 25th | Average | 75% |
| 95 | 37th | Average | 63% |
| 100 | 50th | Average | 1 in 2 |
Questions about an IQ of 90
What percentile is an IQ of 90?
An IQ of 90 is at about the 25th percentile, which means it is higher than about 25% of people of the same age.
Is 90 a high IQ?
No. 90 is in the average range. High IQ usually refers to scores of 120 or 130 and above.
Can an IQ of 90 get into Mensa?
Not on its own. Mensa accepts the top 2% on an approved, supervised test, which is usually 130 or above. 90 is 40 points below that.
How common is an IQ of 90 or higher?
About 75% of people score 90 or higher. In a stadium of 50,000 people, about 37,400 would score at this level or above.
Was an IQ of 90 always classed as average?
No. In David Wechsler's classification for the original Wechsler-Bellevue scale, average started at 91, so a 90 counted as dull-normal. His WAIS table, published in 1958, moved the average range to 90 to 109, and Pearson's current Wechsler reports still treat 90 to 109 as average. The score itself means the same: about a quarter of people score lower.
What mental age is an IQ of 90?
Under the old ratio formula, a 9-year-old with an IQ of 90 would perform like a typical child of about 8 years 1 month, roughly 11 months behind. The idea only works for children: an adult who scores 90 simply did less well than most adults of the same age on the test.
Is an IQ of 90 normal?
Yes. 90 is in the average range of 90 to 109, which covers about half of all people. Nothing about it is unusual.
Why is 90 below 100 if it is average?
100 is the exact middle, but "average" is a band, not a single number. Psychologists call the whole range from 90 to 109 average because the differences within it are small and within a test's margin of error.
Is an IQ of 90 good enough for university?
Yes. Universities select on qualifications, not IQ, and people with average scores succeed on degree courses every year. Effort, interest and study habits make a bigger difference.
Our guide to average IQ explains why the middle is always 100, and what counts as a good IQ score puts the 90s in context. National averages, and why they are disputed, are covered in average IQ by country. Every score range is in the IQ range chart.
A full IQ score of 90 combines several skills. Our guides explain each one: fluid vs crystallized intelligence, abstract reasoning, spatial reasoning, verbal reasoning and processing speed, or try the free pattern recognition test.
What would you score?
Take the free Assessivo IQ test: 36 questions, 25 minutes, and your estimated IQ score and percentile as soon as you finish.
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