IQ Percentile Calculator
Enter any IQ score and the scale it came from — get the percentile, rarity and classification instantly, with the score placed on the bell curve.
What your percentile means
A percentile is the share of the population scoring below you. The 84th percentile means you out-score 84 of a random 100 people; the 16th percentile means 84 of them out-score you. Because the IQ distribution is symmetric around 100, every score has a mirror twin: 115 (84th percentile) mirrors 85 (16th), 130 mirrors 70, and so on.
Percentiles are also the honest way to compare scores from different tests. A number alone is ambiguous — an IQ of 135 is the top ~1% on an SD-15 test but only the top ~2.5% on an SD-24 Cattell scale. Converting to percentile removes the ambiguity, which is exactly what this calculator does.
Quick reference (SD-15)
| IQ | Percentile | Rarity |
|---|---|---|
| IQ 90 | 25th | 1 in 4 |
| IQ 100 | 50th | 1 in 2 |
| IQ 110 | 75th | 1 in 4 |
| IQ 115 | 84th | 1 in 6 |
| IQ 120 | 91st | 1 in 11 |
| IQ 125 | 95th | 1 in 21 |
| IQ 130 | 98th | 1 in 44 |
| IQ 135 | 99th | 1 in 102 |
| IQ 140 | 99.6th | 1 in 261 |
| IQ 145 | 99.9th | 1 in 741 |
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Start the Free IQ TestFrequently asked questions
How is an IQ percentile calculated?
IQ scores follow a normal distribution with mean 100. The score is first converted to a z-score — (IQ − 100) ÷ SD — and the cumulative normal distribution turns that z-score into the share of the population scoring below it. An IQ of 130 on an SD-15 test gives z = 2.0, which corresponds to the 97.7th percentile.
Why does the test's standard deviation matter?
Because the same percentile produces different numbers on different scales. The top 2% is about 131 on an SD-15 test (Wechsler), 132–133 on SD-16 (older Stanford–Binet), and 148 on SD-24 (Cattell). This is why high-IQ societies state requirements as percentiles, and why a "Cattell 148" is not higher than a "Wechsler 135".
What percentile do I need for Mensa?
The 98th percentile — the top 2% of the population. On this calculator, that is an SD-15 score of about 131, verified through a supervised test that Mensa accepts.
Is a percentile more meaningful than the IQ number?
For communication, yes: "top 5%" means the same thing regardless of which test produced it, while a raw number is ambiguous without knowing the scale. Psychologists routinely report both.