Score meaning · Reviewed 2026-09-23
What an IQ of 100 means
An IQ of 100 means the score sits on the mean of a scale whose average was set at 100. On a normal curve with a standard deviation of 15, that is the 50th percentile. Half the area of the curve is at or below 100, and half is above. It is the center of the line, not a grade and not a comment on character.
100 is the mean, by design
The modern IQ scale is built so that the average standard score is 100. Test publishers do that with norms: they give the battery to a reference group and assign 100 to the reference group’s average performance, with 15 points standing for one standard deviation. The number 100 is therefore a choice about the ruler. It is not a discovery that “the average person gets 100 items right.”
On the normal curve this site uses for labels, z at 100 is 0, and the percentile is 50. A score of 95 is about the 37th percentile. A score of 105 is about the 63rd. Those three numbers are all inside the average band this site prints, which runs from 90 to 109. The score chart has the neighboring rows. What average IQ means is about that whole band, not only the midpoint.
What an IQ of 100 does not mean
It does not mean someone answered half the items. A standard score is not a percentage. It does not mean “average effort,” “average schooling,” or “average potential.” It does not locate a person inside a classroom, a job, or a diagnosis. Two people with the same full-scale number can have very different profiles: one strong in words and slow on a timer, another the reverse.
- It is not the bottom of the useful range. The average band is where a large share of the curve lives.
- It is not a promise that every index was 100. Composites can agree while the indexes do not.
- It is not stable to the point. A different day, a different test, or a different language can move the number without a change in the person worth a story.
- It is not something this website can certify for a form.
100 next to 90, 110, and 115
Ninety is about two-thirds of a standard deviation below the mean, near the 25th percentile, and it is still the start of this site’s average band. One hundred and ten is the same distance above the mean, near the 75th percentile, and it is the start of high average. One hundred and fifteen is one full standard deviation up, near the 84th percentile. People often talk as if those gaps were categories of person. On the curve they are distances.
If a report prints 100 with a confidence interval, the interval is the examiner’s statement about measurement error on that instrument. This site does not print an interval. We have not measured a standard error we are willing to claim. Read 100 here as a point label, not as a range we hid.
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.
If this site’s estimate prints 100
The free IQ test can print an overall estimate of 100. That means the five domain scores, averaged and placed on the 100/15 line, landed on the mean of that line. It does not mean the tasks were normed so that the public’s average is 100. The conversion assumes a shape so the parts of the sitting can share a ruler. How scores are made is the honest version of that sentence.
Look at the profile name under the number before you decide the sitting was “flat.” The name is a second sentence: words versus visual structure, and reasoning versus memory and speed. A mean of 100 can still hide a split. The written reading of the domains, the tasks, GAI, and CPI is the one-time sheet. You do not need it to see the 100 or the name. You do need a real WISC or WAIS, not this page, if a school asked for an IQ.
Common questions
Is an IQ of 100 low?
No. It is the average of the scale. Low average on this site’s labels starts below 90.
What percent of people have an IQ of 100?
This page does not have a headcount. On the normal curve, 100 is the 50th percentile, which means half the area is at or below the mean, not that half of people scored exactly 100.
Can I use a score of 100 from this site on a form?
No. The estimate is unnormed and is not a WAIS or WISC.
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
See where a sitting lands
No sign-up. About 30 minutes. The result is an estimate on this scale, not a certified IQ.