IQ percentile calculator
Type an IQ score to see its percentile, how rare it is and its level. It works for tests that use a standard deviation of 15, 16 or 24 points.
The curve is drawn for a standard deviation of 15. A score from a test with another standard deviation is placed by its rarity.
Percentile to IQ
Percentiles on each scale
| IQ | Percentile, SD 15 | Percentile, SD 16 | Percentile, SD 24 |
|---|---|---|---|
| 70 | 2.2 | 3.0 | 10.5 |
| 80 | 9.1 | 10.5 | 20.2 |
| 90 | 25.2 | 26.5 | 33.8 |
| 100 | 50.0 | 50.0 | 50.0 |
| 110 | 74.7 | 73.4 | 66.1 |
| 120 | 90.8 | 89.4 | 79.7 |
| 130 | 97.7 | 96.9 | 89.4 |
| 140 | 99.61 | 99.37 | 95.2 |
| 150 | 99.957 | 99.911 | 98.1 |
| 160 | 99.996 | 99.991 | 99.37 |
The same number is rarer on a scale with a smaller standard deviation.
How is an IQ percentile worked out?
Subtract 100 from the score and divide by the standard deviation of the test. That gives the number of standard deviations from the average. The percentile is the share of the normal curve below that point.
For example, 130 on a 15-point scale is 2 standard deviations above the average, and about 97.7% of the curve lies below it.
Why does the standard deviation matter?
Tests agree that 100 is the average but not on the size of a standard deviation. Most use 15, older Stanford-Binet editions used 16 and the Cattell scale uses 24.
Mensa sets its line at the top 2% whatever the test: 132 on the Stanford-Binet and 148 on the Cattell scale.1
Is a percentile the same as a percentage score?
No. A percentile says how many people score lower than you. A percentage score says how many questions you got right. Someone at the 90th percentile scored higher than 90% of people, whatever share of the questions they answered.
Related pages
Sources
- Mensa International. What is IQ? (read 13 November 2026). www.mensa.org/what-is-iq/
First published 13 November 2026.