What Is the Average IQ? The Basics of Standard Deviation and Distribution
2026-05-01
"What is the average IQ?" is one of the most common questions we hear. The short answer: modern intelligence tests are designed so that the average IQ comes out to 100.
Why Is the Average 100?
IQ is not an absolute quantity—it is a measure of your relative position within your own age group. Scores from large numbers of test takers are collected and then calibrated so that the average lands exactly at 100 and the spread (standard deviation) is 15.
What a Standard Deviation of 15 Means
A standard deviation of 15 means that roughly 68% of people fall within the range of IQ 85 to 115 (the average ±1 SD). About 95% fall within IQ 70 to 130 (±2 SD). In other words, an IQ of 130 or above is the top 2% or so, while an IQ below 70 is the bottom 2% or so. You can check the detailed distribution in our IQ distribution data.
How to Find Out Your Own IQ
To learn your true relative position, a test that measures multiple domains in a balanced way is most effective. BrainRank's free test estimates your IQ, deviation score, and top percentile across four domains (spatial reasoning, pattern recognition, logical reasoning, and classification ability).
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20 questions in about 10 minutes give you your estimated IQ, deviation score, and national ranking.
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