IQ Distribution Data
The theoretical distribution of IQ (mean 100, standard deviation 15). See the percentage in each IQ band and what "1 in how many people" it represents, backed by data.
In brief: IQ follows a normal distribution with a mean of 100 and a standard deviation of 15. About 68% of people fall between IQ 85 and 115 and about 95% between IQ 70 and 130. IQ 130 and above is roughly the top 2.28% (about 1 in 44), and IQ 145 and above is roughly the top 0.13%.
Normal distribution (mean 100, standard deviation 15)
Percentage in each IQ band
55〜70
2.14%
70〜85
13.59%
85〜100
34.13%
100〜115
34.13%
115〜130
13.59%
130〜145
2.14%
145〜160
0.13%
- 55〜70（Borderline）About 1 in 47 people
- 70〜85（Below average）About 1 in 7 people
- 85〜100（Average (lower half)）About 1 in 3 people
- 100〜115（Average (upper half)）About 1 in 3 people
- 115〜130（High）About 1 in 7 people
- 130〜145（Very high）About 1 in 47 people
- 145〜160（Genius level）About 1 in 759 people
Frequently asked questions
- What are the mean and standard deviation of IQ?
- Major modern intelligence tests are standardized so that the mean of an age group is 100 and the standard deviation is 15. An IQ of 100 is exactly the middle.
- What percentile is an IQ of 130 or above?
- On a normal distribution with a mean of 100 and an SD of 15, roughly the top 2.28%, about 1 in 44 people, close to Mensa's admission guideline (the top 2%).
- What is the average IQ range?
- About 68% of people fall between IQ 85 and 115 (the mean plus or minus one standard deviation), which is generally treated as the average range. Roughly half fall between IQ 90 and 109.
- What IQ do you need to be in the top 1%?
- Solving the same model for the cutoff, the top 1% begins at about IQ 135 (z ≈ 2.33), the top 2% at about IQ 131, the top 5% at about IQ 125, and the top 10% at about IQ 119. These are theoretical cutoffs, and a single test carries several points of measurement error.
- Is this distribution table based on actual test takers?
- No. The figures are theoretical values computed analytically from a normal-distribution model with a mean of 100 and an SD of 15, not aggregated from actual test takers.
* Figures are estimates and illustrative values based on a normal distribution model and general findings. They are not aggregated from actual test-taker data.