The short answer is that anything above 100 is above average, and anything above 115 puts you in the top 16 percent of the population. But a raw number on its own means very little. What actually matters is where that number sits relative to everyone else, and that is what this guide explains.
This is the single most misunderstood fact about intelligence testing. The average IQ is not 100 because of some discovery about the human brain. It is 100 because test makers deliberately set it there.
Every major IQ test is standardised against a large representative sample of the population. The raw answers are converted onto a scale where the middle of that sample scores exactly 100. If the population as a whole got better at the test tomorrow, the test would be recalibrated and the average would still be 100.
This means an IQ score is not a measure of how much you know. It is a measure of your rank compared to everyone else who took the same standardised test.
Alongside the average of 100, tests define a standard deviation, which describes how spread out scores are. Most modern tests, including the Wechsler scales, use a standard deviation of 15.
Because IQ scores follow a normal distribution — the familiar bell curve — this single number tells you how common any given score is:
That last figure is why scores above 145 are so rarely seen. Roughly one person in a thousand reaches it.
Percentile is the most useful way to read a score. A percentile of 84 means you scored higher than 84 percent of people. Here is how the standard scale maps out.
| IQ Score | Percentile | Roughly how many people |
|---|---|---|
| 145 | 99.9th | 1 in 1,000 |
| 140 | 99.6th | 1 in 250 |
| 130 | 98th | 1 in 50 |
| 125 | 95th | 1 in 20 |
| 120 | 91st | 1 in 11 |
| 115 | 84th | 1 in 6 |
| 110 | 75th | 1 in 4 |
| 100 | 50th | 1 in 2 |
| 90 | 25th | 1 in 4 |
| 85 | 16th | 1 in 6 |
| 70 | 2nd | 1 in 50 |
Test publishers group scores into descriptive bands. The exact labels vary between tests and have been revised over the years to avoid outdated terminology, but the structure is consistent.
| Range | Classification |
|---|---|
| 130+ | Extremely high / very superior |
| 120–129 | Superior |
| 110–119 | High average |
| 90–109 | Average |
| 80–89 | Low average |
| 70–79 | Borderline |
| Below 70 | Extremely low |
Notice how wide the average band is. Scores from 90 to 109 all count as average, and that band alone contains roughly half the population. A difference of ten or fifteen points in the middle of the range is far less meaningful than people assume.
Even properly administered tests carry a margin of error, typically around four to five points either side. Most reputable reports give a confidence interval rather than a single number for exactly this reason.
Several things move a result without your underlying ability changing at all:
There is also the Flynn effect: measured IQ scores rose substantially across the twentieth century in developed countries, which is why tests are periodically restandardised. Someone scoring 100 on a test from decades ago would not necessarily score 100 today.
IQ is one of the better studied measures in psychology and it does correlate with academic performance and some job performance outcomes. But the correlations are moderate, not deterministic, and they describe group averages rather than individual destinies.
It does not measure creativity, practical judgement, emotional understanding, persistence, or specialist expertise. Plenty of people with average measured IQ substantially outperform higher scorers, because effort and domain knowledge compound over years in a way a ninety minute test cannot capture.
The most sensible way to read a good IQ score is as one data point about a specific set of reasoning skills, on one particular day.
Any score above 100 is above average, since 100 is the population mean. Most people treat 110 and above as a good score, which places you in roughly the top 25 percent. Scores of 120 and above are genuinely uncommon, reached by around 9 percent of people.
The average IQ is 100 by definition. Tests are standardised so the population mean is always 100, with a standard deviation of 15 on most modern tests. Around 68 percent of people score between 85 and 115.
Yes. An IQ of 120 sits at roughly the 91st percentile, meaning you scored higher than about 91 percent of the population. It falls in the superior range on standard classification scales.
Mensa accepts applicants scoring in the top 2 percent. That means about 132 on a test with a standard deviation of 15, or 148 on the Cattell III B scale used by British Mensa.
Relative standing is fairly stable in adulthood, but individual results vary. Sleep, stress, test familiarity and testing conditions can each shift a result by several points, which is why any single score is best treated as an estimate.
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