It is exactly average. On the standard IQ scale, 100 is at roughly the 50th percentile, about 1 in 2 at or above.
An IQ of 100 sits in the average range, higher than about 50.00% of people on a mean-100, SD-15 scale. This is a theoretical model comparison, not an observed population ranking. Here is what that means, and what it does not.
Reference score
100
Percentile
50.00%
At or above
1 in 2
Reference scale
100 mean / 15 SD
Prepared by IQInsight · Calculation guide · Updated
100 is the middle of the scale: average by definition.
IQ scales are built so that the reference mean is 100. With a standard deviation of 15, a score of 100 has a z-score of 0 and sits at the 50th percentile: half of the model distribution falls below it and half at or above it. Average here is a statistical position, not a judgement about ability or potential.
The band from 90 to 109, which common test manuals label average, covers about half of the reference distribution. Moving from 100 to 105 shifts the percentile by about 13 points, a larger change than the same five-point step makes near the top of the scale, because values are densest around the mean.
How test manuals label 100.
Professional tests describe score ranges with standard labels. On the WAIS-IV, 100 falls in the average range; the newer WISC-V calls the same range average. The labels describe ranges on those specific tests and change at fixed boundaries, so a score a point or two from an edge is not meaningfully different from one just across it.
Descriptive classifications used by the WAIS-IV and WISC-V
Score range
WAIS-IV label
WISC-V label
130 and above
Very superior
Extremely high
120–129
Superior
Very high
110–119
High average
High average
90–109 (100)
Average
Average
80–89
Low average
Low average
70–79
Borderline
Very low
69 and below
Extremely low
Extremely low
How precise is one result?
Every test score contains some measurement error. Professionally normed tests report a confidence interval, a band of several points around the score, and two results a few points apart often overlap. IQInsight has not been calibrated against a representative population, so it cannot provide a reliable interval for its estimates.
How the percentile is calculated.
The reference uses a mean of 100 and a standard deviation of 15. First convert the score to a z-score, then find the area below it on the standard normal curve.
Theoretical normal distribution. Mean 100, standard deviation 15. This does not measure your IQ or compare you with IQInsight users.
Put the number in perspective.
In a normal distribution with mean 100 and standard deviation 15, about 50.00% of scores fall at or above 100. That is approximately one in 2. The figure describes the reference model; it is not a count of people we have tested.
The quality of the test matters.
A number alone does not show how accurately it was measured. An established, professionally administered test has supporting evidence and defined interpretation rules. An online exercise without representative norms cannot establish the same conclusions.
Nearby scores on the same scale.
Theoretical percentiles, mean 100 and standard deviation 15
An average score is consistent with success in a wide range of studies and work; the number itself does not select a path. For useful feedback, look at which kinds of problems took longer and which approaches worked, rather than the overall score.
A score alone cannot tell you how a person thinks through a problem. This published sample illustrates a reasoning method; it is not calibrated to a 100 IQ level and does not predict a score.
Double the current term, then add the next counting number, starting with +1: 3, 7, 16, 35, 74. What comes next?
A. 148
B. 149
C. 152
D. 153
Reveal the answer and reasoning
Answer: 153. The additions are +1, +2, +3 and +4. The next transition is 74×2+5=153.
Check an alternative: 148. Doubling 74 leaves out the addition.
Try this approach. Write both parts of every transition and advance the changing part.
This is one of our public sample questions. Seeing the solution may make a future attempt more familiar. Explore the sample report to see how answers are explained.
A few things you might be wondering.
Clear answers, before you begin.
Is an IQ of 100 bad?+
No. 100 is the centre of the scale and the most common region of scores. A single number cannot describe knowledge, skills, effort or interests, and an online estimate is especially limited.
What percentile is an IQ of 100?+
On a scale with mean 100 and standard deviation 15, 100 is at roughly the 50th percentile: about 50.00% of values are at or above it. Tests with a different standard deviation give a different percentile for the same number.
Is 100 a good IQ score?+
On a theoretical scale with mean 100 and standard deviation 15, 100 is in the average range, higher than about 50.00% of people on a mean-100, SD-15 scale. This is a theoretical model comparison, not an observed population ranking. Whether a particular test result supports that interpretation depends on the quality and standardization of that test.
How rare is an IQ of 100?+
Under that normal-distribution model, about 50.00% of values are at or above 100, approximately 1 in 2. This is a mathematical reference, not observed IQInsight user data.
Does this number describe all of my abilities?+
No. IQ scores do not describe every skill, interest, quality or circumstance. A score on an unstandardized online exercise is especially limited and should not be treated as a diagnosis or a prediction of personal success.
Can I compare scores from different tests?+
Only with care. Tests can differ in norms, scales, questions, administration and reliability. Similar-looking numbers are not necessarily equivalent measurements.
Can I get my result without paying?+
Yes. IQInsight provides your estimated score, theoretical percentile and four-area breakdown for free. The optional report explains the answers in more detail.
