On the standard IQ scale the mean is 100 and the standard deviation 15. A score from 90 to 109 is average, 110 to 119 is high average, and 120 or more is superior.
IQ chart
| IQ | Description | Share of people | About |
|---|---|---|---|
| 130 or more | Very superior | 2.3% | 1 in 44 |
| 120–129 | Superior | 6.8% | 1 in 15 |
| 110–119 | High average | 16.1% | 1 in 6 |
| 90–109 | Average | 50% | 1 in 2 |
| 80–89 | Low average | 16.1% | 1 in 6 |
| 70–79 | Borderline | 6.8% | 1 in 15 |
| Under 70 | Extremely low | 2.3% | 1 in 44 |
Labels vary slightly between tests (Wechsler, Stanford-Binet), but the cut-offs at 70, 85, 115 and 130 are the usual ones.
What is a good IQ score?
There is no single threshold, but 115 is higher than 84% of people and 120 than about 91%. Scores of 120, 130 and 140 each have their own page.
What IQ is genius level?
There is no scientific definition of genius. Scores of 145 or more, about 1 person in 740, are often called exceptional.
IQ percentile chart
The percentile tells you what share of people score below you. It is worked out from the normal curve with a mean of 100 and a standard deviation of 15.
| IQ | Percentile | Share of people above (%) |
|---|---|---|
| 70 | 2.3 | 97.7 |
| 85 | 15.9 | 84.1 |
| 90 | 25.2 | 74.8 |
| 100 | 50 | 50 |
| 110 | 74.8 | 25.2 |
| 115 | 84.1 | 15.9 |
| 120 | 90.9 | 9.1 |
| 125 | 95.2 | 4.8 |
| 130 | 97.7 | 2.3 |
| 135 | 99 | 0.98 |
| 140 | 99.6 | 0.38 |
| 145 | 99.9 | 0.13 |
Not every IQ scale is the same
Most modern tests, such as the Wechsler scales, use a standard deviation of 15. Older editions of the Stanford-Binet used 16, and the Cattell Culture Fair test uses 24. The same rarity therefore gives different numbers:
| Rarity | SD 15 | SD 16 | SD 24 |
|---|---|---|---|
| Top 2% (Mensa level) | 130 | 132 | 148 |
| Top 16% | 115 | 116 | 124 |
So an “IQ of 148” on a Cattell scale is about the same as 130 on the Wechsler scale. Always check which scale a score uses.
Wechsler classification
| IQ | Wechsler label |
|---|---|
| 130+ | Very superior / extremely high |
| 120–129 | Superior / very high |
| 110–119 | High average |
| 90–109 | Average |
| 80–89 | Low average |
| 70–79 | Borderline / very low |
| Below 70 | Extremely low |
Frequently asked questions
Is 100 a good IQ?
It is exactly average: higher than half of people.
What is the highest possible IQ?
Most tests stop measuring reliably around 145 to 160; scores above that are extrapolations.
What IQ is the top 1%?
About 135 on a scale with a standard deviation of 15.
Why do some IQ tests give much higher numbers?
They may use a standard deviation of 24 instead of 15, so the same rarity produces a bigger number.
Sources
- Wechsler, D. (2008). WAIS-IV: Technical and interpretive manual. Pearson.
- Neisser, U. et al. (1996). Intelligence: Knowns and unknowns. American Psychologist, 51(2), 77–101.