Where 100 sits on the bell curve
This score is exactly the average: the scale is built so that 100 is its middle. The shaded part of the curve, everyone who scores lower, covers about 50.0% of people.
What an IQ of 100 means
100 sits in the middle of the Average range (90 to 109). It is exactly at the mean of 100, so about 50 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 99 and 101 reflect almost the same performance.
Whether 100 counts as a good IQ score depends on the comparison: against everyone, or against the people you study or work with.
How rare is an IQ of 100?
If scores follow the standard bell curve, this is how many people you would expect to reach this score or higher:
- In a class of 30: about 15
- In an office of 250: about 125
- In a town of 10,000: about 5,000
- In a city of 1 million: about 500,000
100 compared with nearby scores
| IQ | Percentile | Range | How rare |
|---|---|---|---|
| 90 | 25th | Average | 1 in 1.3 |
| 95 | 37th | Average | 1 in 1.6 |
| 100 | 50th | Average | 1 in 2 |
| 105 | 63rd | Average | 1 in 2.7 |
| 110 | 75th | High Average | 1 in 4 |
"How rare" counts people at that score or higher.
100 and the usual reference points
- Exactly 100: the average by definition.
- 15 points below 115, one standard deviation above average (about the 84th percentile).
- 30 points below 130, two standard deviations above average and the usual Mensa line (top 2%).
- 45 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 100 is best read as "probably between 95 and 105". Short 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 100 a good IQ score?
An IQ of 100 is in the Average range (90 to 109) and higher than about 50% of people. About 1 in 2 people score 100 or higher.
What percentile is an IQ of 100?
An IQ of 100 is at about the 50th percentile. On the standard scale (mean 100, standard deviation 15) it is +0.00 standard deviations from the average.
How rare is an IQ of 100?
About 1 in 2 people score 100 or higher, which is 50.0% of the population.
Is 100 an average IQ?
Yes. Half of all people score between 90 and 109, the Average range, and 100 is inside it: higher than about 50 in 100 people.
How accurate is an online IQ score of 100?
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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