IQ Percentile Calculator
An IQ of 100 is the 50th percentile, 115 is the 84.1th, 130 is the 97.7th and 145 is the 99.87th. Enter any score for its percentile.
Percentile of an IQ of 120 (SD 15)
90.9thSuperior
An IQ of 120 is higher than about 90.9% of people.
- +1.33
- Z-score
- 1 in 11
- Score this high or higher
IQ 120: what it means. How rare is an IQ of 120 gives it as 1 in N.
IQ to percentile table
Every row is computed from the normal curve with an average of 100 and a standard deviation of 15, the scale used by the WAIS, the Stanford-Binet 5 and most modern tests.
| IQ | Percentile | Z-score | Higher than |
|---|---|---|---|
| IQ 70 | 2.28th | -2.00 | 2.28% |
| IQ 75 | 4.78th | -1.67 | 4.78% |
| IQ 80 | 9.12th | -1.33 | 9.12% |
| IQ 85 | 15.9th | -1.00 | 15.9% |
| IQ 90 | 25.2th | -0.67 | 25.2% |
| IQ 95 | 36.9th | -0.33 | 36.9% |
| IQ 100 | 50th | +0.00 | 50% |
| IQ 105 | 63.1th | +0.33 | 63.1% |
| IQ 110 | 74.8th | +0.67 | 74.8% |
| IQ 115 | 84.1th | +1.00 | 84.1% |
| IQ 120 | 90.9th | +1.33 | 90.9% |
| IQ 125 | 95.2th | +1.67 | 95.2% |
| IQ 130 | 97.7th | +2.00 | 97.7% |
| IQ 135 | 99.0th | +2.33 | 99.0% |
| IQ 140 | 99.62th | +2.67 | 99.62% |
| IQ 145 | 99.87th | +3.00 | 99.87% |
| IQ 150 | 99.96th | +3.33 | 99.96% |
| IQ 155 | 99.99th | +3.67 | 99.99% |
| IQ 160 | 99.9968th | +4.00 | 99.9968% |
130 is not quite the 98th percentile
An IQ of 130 is the 97.7th percentile. The 98th percentile sits slightly higher, at about 130.8. Both get called "the top 2%", and the gap is under one IQ point.
Percentiles are usually rounded and IQ scores are whole numbers, so reports often blur the two. Near a cut-off, one point is well inside the margin of error of the test.
To go the other way and find the score for a percentile, use the percentile to IQ converter. For the same score as "1 in N" and a head count, use how rare is my IQ.
SD 15, SD 16 and SD 24 side by side
Tests build the same bell curve with a different spread, so the same level of ability gets a different number. Match scores by z-score or percentile, never by the raw figure.
| Z-score | Percentile | SD 15 (Wechsler) | SD 16 (Stanford-Binet) | SD 24 (Cattell) |
|---|---|---|---|---|
| -2.00 | 2.28th | 70 | 68 | 52 |
| -1.00 | 15.9th | 85 | 84 | 76 |
| +0.00 | 50th | 100 | 100 | 100 |
| +1.00 | 84.1th | 115 | 116 | 124 |
| +1.50 | 93.3th | 122.5 | 124 | 136 |
| +2.00 | 97.7th | 130 | 132 | 148 |
| +2.50 | 99.4th | 137.5 | 140 | 160 |
| +3.00 | 99.87th | 145 | 148 | 172 |
| +4.00 | 99.9968th | 160 | 164 | 196 |
A Cattell 148, a Stanford-Binet 132 and a Wechsler 130 are all two standard deviations up, so all about the 98th percentile. The Mensa IQ requirement page uses exactly this to give the cut-off for each test.
How the calculation works
IQ scores are built to follow a bell curve, so the percentile is a two-step job.
- Find the z-score. Subtract 100 and divide by the standard deviation. For 130 on SD 15 that is (130 − 100) ÷ 15 = +2.0.
- Read the curve. The share of a normal curve below z = +2.0 is 97.7%. That is the percentile.
Two cautions. Real tests are normed on real samples, so their tables can differ slightly from the smooth curve, most of all at the extremes. And every score has a margin of error of several points, so a percentile is best read as the middle of a range: the IQ confidence interval calculator shows how wide.
Example: a report says 118 on SD 15. The z-score is (118 − 100) ÷ 15 = +1.2, which puts the score at the 88.5th percentile. An online estimate is a rougher input than a clinical report, so treat the percentile as a guide to the neighbourhood, not a rank.
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<p><a href="https://lifescoretest.com/tools/iq-percentile-calculator">IQ percentile calculator</a> by LifeScore</p>Frequently asked questions
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