Free tool
IQ percentile calculator
Type an IQ score to see its percentile, how rare it is and its classification label. Choose the scale your score came from: most modern tests use a standard deviation of 15.
Do not have a score yet? Take the IQ Octopus test and get your estimated IQ and percentile.
- Percentile
- 90.9Higher than about 90.9% of people.
- Rarity
- About 1 in 11score 120 or higher.
- Classification
- SuperiorClearly above average: between about one and a third and two standard deviations above the mean.
- On other scales
- SD 16: 121 · SD 24: 132The same percentile, printed on a different scale.
How to read the result
Percentile is the share of people expected to score below this number. A percentile of 90 means higher than about 90% of people the same age.
Rarity turns the tail of the curve into a count: for scores above 100, about how many people you would need to meet to find one scoring this high or higher; below 100, this low or lower.
Classification uses the WAIS-IV labels, from Extremely Low (69 and below) to Very Superior (130 and above) (Wikipedia: IQ classification). The labels describe ranges; a point or two either side of a boundary is within the measurement error of any test.
Why the scale matters
Modern tests standardize scores to a mean of 100 and a standard deviation of 15 (Wikipedia: Intelligence quotient). Older Stanford-Binet forms used 16, and the Cattell Culture Fair III scale uses 24 (Wikipedia: IQ classification). The same percentile prints as a different number on each, which is why the calculator asks. If you have a percentile instead of a score, use the percentile to IQ converter.
The math
The calculator converts your score to a z-score, (IQ − 100) ÷ SD, then reads the share of the normal curve below that point. That is why about 68% of people fall between 85 and 115 and about 95% between 70 and 130 (the 68-95-99.7 rule). Nothing here is estimated from survey data: it is the shape of the scale itself.
Sources
- Intelligence quotient. Wikipedia. en.wikipedia.org/wiki/Intelligence_quotient
- IQ classification. Wikipedia. en.wikipedia.org/wiki/IQ_classification
- 68-95-99.7 rule. Wikipedia. en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule