These examples use an idealized normal distribution with mean 100 and standard deviation 15: 100 is the 50th percentile, 115 roughly the 84th, 130 the 97.7th and 145 about the 99.9th. Actual interpretation requires the instrument's norms. This conversion does not validate a score from our site.
The full percentile table
Percentile means the share of the population scoring at or below a given point. Someone at the 84th percentile scored higher than 84 of every 100 people.
| Score | Percentile | People who score lower | Rarity |
|---|---|---|---|
| 145 | 99.9th | 999 in 1,000 | About 1 in 740 |
| 140 | 99.6th | 996 in 1,000 | About 1 in 250 |
| 135 | 99th | 99 in 100 | About 1 in 100 |
| 130 | 97.7th | About 98 in 100 | About 1 in 44 |
| 125 | 95th | 95 in 100 | About 1 in 20 |
| 120 | 91st | 91 in 100 | About 1 in 11 |
| 115 | 84th | 84 in 100 | About 1 in 6 |
| 110 | 75th | 3 in 4 | About 1 in 4 |
| 105 | 63rd | Almost 2 in 3 | Common |
| 100 | 50th | Half | The midpoint |
| 95 | 37th | More than 1 in 3 | Common |
| 90 | 25th | 1 in 4 | About 1 in 4 |
| 85 | 16th | 16 in 100 | About 1 in 6 |
| 80 | 9th | 9 in 100 | About 1 in 11 |
| 70 | 2nd | 2 in 100 | About 1 in 44 |
Notice how the percentiles compress at the top. Moving from 100 to 115 takes you past 34% of the population. Moving from 130 to 145, the same 15-point step, takes you past barely 2%. That compression is why small differences between high scores mean much less than they look like they do.
Where the numbers come from
For the examples here, assume a normal distribution with mean 100 and standard deviation 15. Standardized instruments use their own norm samples and conversion procedures; check the relevant manual.
That gives the familiar bands: about 68% of people fall within one standard deviation of the mean, so between 85 and 115. Roughly 95% fall within two, so between 70 and 130. About 99.7% fall within three, so between 55 and 145.
One consequence catches people out. Because the scale is defined relative to a reference population, a score is only meaningful against the group the test was normed on. A test normed on university students will place the same person lower than one normed on the general adult population, and neither result is wrong.
Why some tests use a standard deviation of 16 or 24
Not every test uses 15. The Stanford-Binet historically used 16, and the Cattell III B uses 24. Those choices change what a given number means quite dramatically.
American Mensa lists a qualifying score of 132 for older Stanford Binet tests and 130 for Stanford Binet 5. Its Cattell requirement is 148. Accepted scores are test-specific; check the current requirements of your national Mensa organization.
Check the instrument and scale rather than assuming a standard deviation. Different scales and norm samples can change how the same number should be interpreted.
What a percentile does not tell you
A confidence interval depends on the instrument, its reliability and the reporting method. Do not apply a universal margin of five points. Our illustrative scores have no established clinical confidence interval.
Percentiles also flatten the profile. Two people at the 91st percentile can have completely different cognitive shapes, one carried by verbal ability and the other by spatial reasoning. For anything practical, the subtest pattern is more useful than the rank.
And the rank says nothing about outcomes. Cognitive ability predicts job performance and academic results moderately well, more strongly as tasks get more complex, but it competes with conscientiousness, opportunity, and health in explaining where people end up.
Source details: American Mensa
Questions people also ask
What percentile is an IQ of 130?
The 97.7th, on the standard scale where one standard deviation is 15 points. That means roughly 2.3% of people score at or above 130, or about one person in 44. It is the conventional threshold for the gifted band.
Is the 50th percentile a bad score?
On an IQ scale standardized to a mean of 100, 100 is the reference average. Percentiles describe position within that test's norm group. The midpoint does not make any individual score a deficiency, and an illustrative score from this site is not a validated population ranking.
Keep reading
- Are Online IQ Tests Accurate?What separates a decent online test from a worthless one.
- What IQ Score Do You Need for Mensa?Top 2%, and why the qualifying number differs by test.
- Signs of High Intelligence (And the Myths)What the research supports, and the popular signs that fail.
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