Where 90 sits on the bell curve
This score is 10 points below the average of 100, or 0.67 standard deviations. The shaded part of the curve, everyone who scores lower, covers about 25.2% of people.
What an IQ of 90 means
90 sits at the start of the Average range (90 to 109). It is 0.67 standard deviations below the mean of 100, so about 25 in 100 people score lower.
The Average range runs from 90 to 109. Range names come from the Wechsler scales; they are labels for parts of the curve, not hard lines, so 89 and 91 reflect almost the same performance.
Whether 90 counts as a good IQ score depends on the comparison: against everyone, or against the people you study or work with.
How common is an IQ of 90 or lower?
If scores follow the standard bell curve, this is how many people you would expect to score this low or lower:
- In a class of 30: about 7.6
- In an office of 250: about 63
- In a town of 10,000: about 2,525
- In a city of 1 million: about 252,493
90 compared with nearby scores
| IQ | Percentile | Range | How rare |
|---|---|---|---|
| 80 | 9th | Low Average | 1 in 1 |
| 85 | 16th | Low Average | 1 in 1.2 |
| 90 | 25th | Average | 1 in 1.3 |
| 95 | 37th | Average | 1 in 1.6 |
| 100 | 50th | Average | 1 in 2 |
"How rare" counts people at that score or higher.
90 and the usual reference points
- 10 points below 100, the average by definition.
- 25 points below 115, one standard deviation above average (about the 84th percentile).
- 40 points below 130, two standard deviations above average and the usual Mensa line (top 2%).
- 55 points below 145, three standard deviations above average (about 1 in 741).
How much to trust a single score
No test measures IQ exactly. Clinical tests such as the Wechsler scales report a confidence interval of roughly 5 points either side, so a measured 90 is best read as "probably between 85 and 95". Unsupervised online tests carry wider ranges, which is why our free test shows a 90% range next to every result.
Scores also move between sittings. Tiredness, stress and practice with the puzzle types can each shift a result by a few points, so the range name tells you more than the exact number.
Frequently asked questions
Is 90 a good IQ score?
An IQ of 90 is in the Average range (90 to 109) and higher than about 25% of people. About 1 in 4 people score 90 or lower.
What percentile is an IQ of 90?
An IQ of 90 is at about the 25th percentile. On the standard scale (mean 100, standard deviation 15) it is -0.67 standard deviations from the average.
How common is an IQ of 90?
About 1 in 4 people score 90 or lower.
Is 90 an average IQ?
Yes. Half of all people score between 90 and 109, the Average range, and 90 is inside it: higher than about 25 in 100 people.
How accurate is an online IQ score of 90?
Treat it as a range, not an exact number. Clinical tests report a confidence interval of roughly 5 points either side, and short online tests have wider ranges, so read any single result as a band rather than an exact point.
Nearby IQ scores
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