What an IQ of 109 means
An IQ of 109 is higher than about 72.5% of people: roughly 1 in 4 score 109 or more. It is in the average range, 0.6 standard deviations above the average of 100.
The amber band is the likely range on a retake of our test, 9 points either side. The curve is the normal distribution with a mean of 100 and a standard deviation of 15.
Is an IQ of 109 good?
It is an average score, the most common result there is. About 49% of people score between 90 and 109.
What percentile is an IQ of 109?
An IQ of 109 is at the 72nd percentile: it is higher than 72.5% of people on a scale with a mean of 100 and a standard deviation of 15.
Tests that use a different standard deviation give the same rarity a different number: about 110 on a 16-point scale such as older Stanford-Binet editions, and about 114 on the 24-point Cattell scale.
How rare is an IQ of 109?
About 1 in 4 people score 109 or higher. In a group of 1,000 people, about 274 would be expected to score that high or higher.
How much could a retake change it?
No test gives the same score twice. The likely range is where about 90 in 100 retakes would land, and its width depends on how reliable the test is.1
| Test | Margin of error | Likely range |
|---|---|---|
| Our test (reliability 0.87) | ±9 | 100 to 118 |
| A test with reliability 0.90 | ±8 | 101 to 117 |
| A test with reliability 0.95 | ±6 | 103 to 115 |
The margin is 1.645 standard errors of measurement, which covers about 90% of retakes.
What an IQ of 109 does not tell you
A score describes how someone did on one set of reasoning tasks on one day. It does not measure what a person knows, how hard they work or what they will achieve.
An online test is for interest. For a score that counts for school, work or health, a psychologist can give a full assessment in person.
Nearby scores
Sources
- American Educational Research Association, American Psychological Association and National Council on Measurement in Education (2014). Standards for Educational and Psychological Testing, chapter 2: Reliability/Precision and Errors of Measurement. www.testingstandards.net/open-access-files.html
First published 13 November 2026.