IQ score chart: scores, percentiles and what they mean
This chart converts an IQ score into a percentile, which is the share of people who score lower. It uses the standard scale: average 100, standard deviation 15.
IQ to percentile
| IQ score | Percentile | Meaning |
|---|---|---|
| 55 | 0.1 | Higher than about 1 in 1,000 |
| 70 | 2 | Higher than 2 in 100 |
| 80 | 9 | Higher than 9 in 100 |
| 85 | 16 | One standard deviation below average |
| 90 | 25 | Lower end of the average range |
| 100 | 50 | Exactly average |
| 110 | 75 | Upper end of the average range |
| 115 | 84 | One standard deviation above average |
| 120 | 91 | Higher than 91 in 100 |
| 130 | 98 | Higher than 98 in 100 |
| 140 | 99.6 | Higher than about 996 in 1,000 |
| 145 | 99.9 | Higher than about 999 in 1,000 |
How to read it
If your IQ is 115, your percentile is about 84. That means roughly 84 out of 100 people in the comparison group scored lower than you. It does not mean you got 84 percent of the questions right.
Standard deviation in plain words
The standard deviation (SD) is a measure of how spread out scores are. On the usual IQ scale one SD is 15 points. About 68 percent of people fall within one SD of the average (85 to 115), about 95 percent within two SDs (70 to 130), and about 99.7 percent within three SDs (55 to 145).
Some older tests use an SD of 16 or 24, which gives different numbers for the same performance. Check which scale a test uses before comparing scores.
A word of caution for online tests
The chart above is exact maths for a perfect bell curve. A short online test gives a noisy estimate, so a score of 112 on one test could easily be 105 or 120 on another. Look at the percentile as a rough guide, not a precise ranking.