Percentile to IQ Converter
The 90th percentile is an IQ of about 119. The 98th is about 131, and the 99th about 135. Enter any percentile for its IQ, or switch direction to go back.
Enter 0.01 to 99.99. For the 99th percentile, type 99.
IQ at the 99.0th percentile (SD 15)
135Very superior
The 99.0th percentile is an IQ of about 135 on a scale with a standard deviation of 15. Unrounded, it is 134.9.
- +2.33
- Z-score
- Top 1%
- Share scoring this high or higher
IQ 135: what it means. For rarity as "1 in N", see how rare is my IQ.
What IQ is each percentile?
The answer for the percentiles people ask about most. Computed from the normal curve with an average of 100.
| Percentile | IQ (SD 15) | IQ (SD 16) | Share this high |
|---|---|---|---|
| 50th | 100 | 100 | Top 50% |
| 75th | 110 | 111 | Top 25% |
| 80th | 113 | 113 | Top 20% |
| 90.0th | 119 | 121 | Top 10% |
| 95.0th | 125 | 126 | Top 5% |
| 98.0th | 131 | 133 | Top 2% |
| 99.0th | 135 | 137 | Top 1% |
| 99.90th | 146 | 149 | Top 0.1% |
To go from a score to its exact percentile and z-score, use the IQ percentile calculator.
How a percentile becomes an IQ
A percentile is the share of a comparison group that scored below you. IQ scores are built to follow a bell curve with an average of 100, so each percentile has one matching score.
The steps run in reverse of the usual calculation. Find the z-score that has your percentile of the curve below it. Then multiply by the standard deviation and add 100. The 99th percentile has a z-score of +2.33, so the IQ is 100 + 2.33 × 15 = 135 on SD 15, and 100 + 2.33 × 16 = 137 on SD 16.
The Wechsler tests use SD 15. The older Stanford-Binet used SD 16 and the Cattell scale used SD 24. Always check which scale a score is on before you convert. The Mensa IQ requirement page shows the same cut-off on each one.
One caution. A percentile from a published test comes from that test's own norm sample, and a percentile quoted by an online test is only as good as its norms. The converter gives the IQ on a smooth theoretical curve. Use it to translate between scales and to sense-check a report, not to overrule one.
Frequently asked questions
What IQ is the 99th percentile?
What IQ is the 90th percentile?
What IQ is the 98th percentile?
What IQ is the 50th percentile?
What IQ is the 95th percentile?
What is the difference between SD 15 and SD 16?
What is a z-score?
Is a percentile the same as a percentage?
Why is the result a whole number?
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