Reference
IQ classification ranges
Every IQ test attaches a descriptive label to a score range. The labels have been rewritten repeatedly, and the direction of travel says something about the field.
The current bands
These are the Wechsler classification ranges, which most English-language tests follow. The share column is not a survey result; it is what a normal distribution produces by construction.
| Score range | Current label | Share of people | Percentile range |
|---|---|---|---|
| 130 and above | Extremely high | 2.2% | 98th percentile and up |
| 120–129 | Very high | 6.7% | 91st–97th percentile |
| 110–119 | High average | 16.1% | 75th–90th percentile |
| 90–109 | Average | 50% | 25th–74th percentile |
| 80–89 | Low average | 16.1% | 9th–24th percentile |
| 70–79 | Very low | 6.7% | 2nd–8th percentile |
| 69 and below | Extremely low | 2.2% | Below the 2nd percentile |
Two things follow from the share column. Half of everyone is in the average band, which is the most under-appreciated fact about IQ. And the two extreme bands together contain about one person in twenty-three, which makes them far less populated than the amount written about them suggests.
How the labels changed
The vocabulary of IQ classification has been revised in every generation, and each revision moved in the same direction: away from words that describe a person and towards words that describe a score.
| Edition | Labels used |
|---|---|
| Terman, 1916 | ≥140 “genius or near genius”, 90–110 “normal”, ≤70 “definite feeble-mindedness” |
| Wechsler, 1939 | ≥128 “very superior”, 91–110 “average”, ≤65 “defective” |
| WAIS-III, 1997 | ≥130 “very superior”, 90–109 “average”, ≤69 “extremely low” |
| WAIS-IV, 2008 | ≥130 “very superior”, 90–109 “average”, ≤69 “extremely low” |
| WAIS-5, 2024 | Descriptive bands only — “extremely high” through “extremely low”, with the older value-laden words dropped |
The terms in the 1916 column are the source of several English insults. Moron, imbecile and idiot were technical classifications with specified score ranges, introduced by psychologists as neutral replacements for older words, and each one became a playground taunt within a generation. This pattern — a clinical term acquiring the stigma of what it describes and being replaced — is known in linguistics as the euphemism treadmill, and IQ classification is its most-cited example.
The current generation of labels is the first to abandon the pattern by design. WAIS-5 uses purely descriptive bands with no evaluative content: extremely high, very high, high average, average, low average, very low, extremely low. There is no “superior” and no “defective”, because both words make a claim about the person rather than the measurement.
Terman used it in 1916 for scores above 140. No modern test publisher uses the word, because it implies a category of person rather than a region of a distribution. When you see an IQ chart with “genius” on it, you are looking at a 1916 classification reprinted a century late.
Three ways the bands get misread
Treating a band as a category of person. The bands are arbitrary cuts through a continuous distribution. Nothing changes between 109 and 110 except which row of a table you fall in, and measurement error means you could land in either row on different days.
Reading the top band as rare-and-special and the bottom as a diagnosis. Both extreme bands contain about 2.2 percent of people. A score below 70 is one criterion for intellectual disability, never the only one — adaptive functioning assessment is required alongside it, and a score alone is not a diagnosis.
Comparing labels across tests. Different instruments use different band boundaries and different words for the same range. A “superior” on one test and a “very high” on another may describe identical performance.
Classification on other scales
The bands above assume a standard deviation of 15. On a scale with a different spread, the same labels sit at different numbers.
| Band | SD 15 (Wechsler) | SD 16 (older Stanford–Binet) | SD 24 (Cattell) |
|---|---|---|---|
| 98th percentile | 131 | 133 | 148 |
| 91st percentile | 120 | 121 | 132 |
| 75th percentile | 110 | 111 | 116 |
| 50th percentile | 100 | 100 | 100 |
| 25th percentile | 90 | 89 | 84 |
| 9th percentile | 80 | 79 | 68 |
This is why an IQ figure quoted without its scale is not interpretable, and why comparisons between scores from different tests are usually meaningless. More on the scale problem.
Questions
Questions people ask
What are the IQ classification ranges?
On the current Wechsler scale: 130 and above extremely high, 120–129 very high, 110–119 high average, 90–109 average, 80–89 low average, 70–79 very low, and 69 and below extremely low.
What percentage of people have an IQ over 130?
About 2.2 percent, which is roughly one person in forty-five. This is Mensa's entry requirement and the most common gifted-programme threshold.
Is there a genius IQ range?
Not on any modern test. Terman used 'genius' for scores above 140 in 1916; publishers abandoned that vocabulary because it describes a category of person rather than a region of a distribution.
What is considered a low IQ?
Scores below 70 fall in the extremely low band, about 2.2 percent of people. A score alone is never a diagnosis — intellectual disability criteria require adaptive functioning assessment alongside it.
Why did the IQ labels change?
Because each generation of clinical terms acquired the stigma of what it described and became an insult. Current labels are purely descriptive by design, with the evaluative words removed.
Find out where you land
Ten reasoning questions, an instant band and an explanation for every answer.