Score chart · Reviewed 2026-09-23
IQ score chart and percentiles
This chart converts an IQ-style score into a percentile on a normal curve with a mean of 100 and a standard deviation of 15. The percentiles are the area under that curve. They are not a sample this laboratory collected, and they do not turn the nine-task estimate into a normed test.
How to read a percentile on this chart
Find the score in the first column. The z column is how many standard deviations that score sits from 100: (score − 100) / 15. The percentile is the share of a standard normal curve at or below that z, rounded to one decimal the same way the result page rounds it. “Top” is 100 minus that percentile, so a 90.9th percentile is about the top 9.1 percent of the curve.
A percentile is not “percent correct,” and it is not a rank among people who took this website’s test. If a manual prints a different percentile for the same number, the manual is using its own norms. Use the manual for that test. Use this chart when you are reading a 100/15 label and you want the curve, not a publisher’s table.
IQ score chart
| IQ | z | Percentile | About the top | Band on this site |
|---|---|---|---|---|
| 70 | −2.00 | 2.3rd | 97.7% | Borderline |
| 80 | −1.33 | 9.1st | 90.9% | Low average |
| 85 | −1.00 | 15.9th | 84.1% | Low average |
| 90 | −0.67 | 25.2nd | 74.8% | Average |
| 100 | 0 | 50th | 50% | Average |
| 110 | +0.67 | 74.8th | 25.2% | High average |
| 115 | +1.00 | 84.1st | 15.9% | High average |
| 120 | +1.33 | 90.9th | 9.1% | Superior |
| 125 | +1.67 | 95.2nd | 4.8% | Superior |
| 130 | +2.00 | 97.7th | 2.3% | Very superior |
| 145 | +3.00 | 99.9th | 0.1% | Very superior |
The far right tail is clamped on the result page so a label never prints past the 99.9th or below the 0.1st. A score of 145 is already in that clamp. Do not invent a more precise “one in a million” figure from this table. What an IQ of 100 means, 120, and 130 each take one row and stay there.
Why the chart does not count people
Between 90 and 110 the curve holds about half its area: the 74.8th percentile minus the 25.2nd is 49.6 percentage points. That is why “most scores are average” can be true of a normal scale even when nobody has published a headcount. It is a description of the shape we assumed, which is the shape the 100/15 convention uses. It is not a finding about visitors to this site.
Real test scores are lumpy. Age bands, education, language, and the day’s effort all move a sitting. A chart that ignores those things will look cleaner than a psychologist’s table. Clean is not the same as true for a person. If the question is “where does my child’s WISC composite sit,” read the percentile printed on the report. The report’s norms already did the age adjustment this chart refuses to fake.
The nine-task test on this site prints numbers on a conventional mean of 100 and a standard deviation of 15 so the parts of one sitting can be compared. That conversion is not a census norm, not age-normed, and not a diagnosis. A qualified examiner and the publisher’s manual are what a school, a clinic, a job, or a visa can use.
Using the chart with this site’s estimate
After the free IQ test, the result page shows an overall IQ estimate, a percentile label from this same curve, a band, and a profile name. The percentile describes the number on the line. It does not mean we measured you against a reference group. The method page says how a raw task becomes that number. There is no reliability coefficient and no standard error on the sheet, because those would be invented if we printed them.
If you are holding a WISC or WAIS, you do not need this chart to subtract two official composites. The GAI calculator does that and nothing else. If you have no report, the test is the place to start. The chart will still be here when you want to translate the estimate into a percentile without pretending the percentile is a norm.
Common questions
What percentile is an IQ of 100?
On a normal curve with mean 100 and SD 15, 100 is the 50th percentile. Half the area is at or below the mean.
What percentile is an IQ of 130?
130 is two standard deviations above 100. On this curve that is the 97.7th percentile, about the top 2.3 percent of the area.
Is this chart a WAIS or WISC norm table?
No. It is the mathematical normal curve. A publisher’s norms can differ, and they include age. Use the report you were given for an official score.
Where to go next
The GAIvsIQ laboratory keeps one URL for each job. This note does not replace the instrument it points to.
Ready when you are
Put a sitting on the line
Nine tasks, about 30 minutes, no sign-up. The result uses this curve as a label, not as a norm.