IQ score chart and what each band means
On the standard scale the mean is 100 and one standard deviation is 15 points. That single sentence fixes how rare every score is, because the distribution is assumed to be normal.
The ranges
130 and above is Very Superior, reached by about 2 in 100. 120 to 129 is Superior, about 7 in 100. 110 to 119 is High Average. 90 to 109 is Average and holds roughly half of everybody. 80 to 89 is Low Average, 70 to 79 Borderline, and below 70 sits at the bottom 2 per cent.
Reading percentiles instead of labels
The label is a convenience; the percentile is the measurement. A score of 115 is the 84th percentile, meaning 84 per cent of the reference group scores below it. The gap between 100 and 115 covers far more people than the gap between 130 and 145.
Why the same person can get two different numbers
A score is always relative to a norm group and an instrument. Sit a test normed on a different population, or one with a 16-point standard deviation, and the figure moves without your reasoning changing at all.
Scored against age, education and area norms. Free certificate with a QR code anyone can verify.
Questions people ask
What percentile is an IQ of 120?
Roughly the 91st percentile on a mean 100, SD 15 scale — about 9 people in 100 score at or above it.
Is 100 exactly average?
Yes, by construction. The scale is defined so the reference group averages 100.