Free iq percentile calculator
See where your IQ ranks in two seconds. Enter your score, pick the test scale (SD 15 Wechsler, 16 or 24 Cattell), and the calculator returns your IQ percentile, z-score, classification, and how rare the score is — plus a full IQ percentile chart — updated live, as you type.
On this page16 sections
| IQ range | Classification |
|---|---|
| 130 and above | Very Superior |
| 120–129 | Superior |
| 110–119 | High Average |
| 90–109 | Average |
| 80–89 | Low Average |
| 70–79 | Borderline |
| 69 and below | Extremely Low |
A ranking of one test score, not a measure of worth. What it does and doesn't tell you
Results are estimates. Consult a professional.
What is an IQ percentile?
An IQ percentile tells you where an IQ score ranks among everyone else who takes the test. If your score is in the 90th percentile, you scored higher than 90% of the population — and only 10% scored higher than you. The 50th percentile is exactly average, which is an IQ of 100. This IQ percentile calculator takes your score and returns that ranking instantly, along with your z-score, a classification band, and how rare the score is.
The key thing to understand is that an IQ is already a normed score, not a raw count of right answers. Test-makers deliberately scale the results so that the average is 100 and the scores spread out in a bell curve. That design is exactly what makes a percentile computable: because the shape of the distribution is fixed, your score alone is enough to place you in it.
How IQ percentile is calculated
IQ scores are constructed to follow a normal distribution — the familiar bell curve, clustered around 100 with fewer and fewer people at the extremes. Because the mean (100) and the standard deviation (how spread out the scores are) are both fixed by the test, a percentile can be computed from just those two numbers plus your score.
The calculator first works out your z-score — how many standard deviations your IQ sits above or below 100. It then feeds that z-score into the standard-normal cumulative distribution function (CDF), which converts it into the share of the population scoring below you. Expressed as a percent, that share is your percentile.
Because the curve is symmetric, an IQ of exactly 100 always lands at the 50th percentile, one standard deviation above (115 on the Wechsler scale) lands near the 84th, and one standard deviation below (85) lands near the 16th. The maths is identical for every test — only the standard deviation changes, which is why the calculator asks which scale your score came from.
A worked example using the IQ percentile calculator
Priya scored 120 on a Wechsler-style test (standard deviation 15) and wants to know what that means. Here is exactly how the calculator places her.
- Find the z-score. Her IQ (120) minus the mean (100) is 20. Divided by the standard deviation (15): 20 ÷ 15 = z ≈ 1.33. She is about one and a third standard deviations above average.
- Convert the z-score to a percentile. Feeding z ≈ 1.33 into the standard-normal CDF gives about 0.909 — so roughly 91% of people score below 120.
- Read the classification and rarity. A z of 1.33 falls in the Superior band, and the nearer (upper) tail is about 9%, so a score this high or higher is reached by roughly 1 in 11 people.
What does my IQ percentile actually mean?
Your percentile is the percentage of people who scored lower than you on the same scale. An 80th percentile means you scored higher than 80 out of every 100 people, and 20 scored higher than you. It is the same number whether you phrase it as "80th percentile" or "higher than 80%" — two ways of saying one thing.
- 50th percentile — exactly average; an IQ of 100. Half score lower, half score higher.
- 84th percentile — one standard deviation above average (IQ 115 on the Wechsler scale).
- 16th percentile — one standard deviation below average (IQ 85 on the Wechsler scale).
- 98th / 2nd percentile — roughly two standard deviations out (IQ 130 or 70) — the upper and lower edges of the common range.
The IQ bell curve and standard-deviation scales
Every common IQ test is normed to a mean of 100, but they do not all use the same standard deviation — and the standard deviation is what decides how far a given score sits from the middle. That is why a score of 130 is not always the same percentile: it depends on the scale.
| Scale (standard deviation) | Tests that use it | z-score for IQ 130 | Percentile for IQ 130 |
|---|---|---|---|
| SD 15 | Wechsler (WAIS / WISC), Stanford-Binet 5 | 2.00 | 97.7th |
| SD 16 | Cattell Culture Fair (modern) | 1.88 | 97.0th |
| SD 24 | Cattell (original scale) | 1.25 | 89.4th |
An IQ of 130 reaches a higher percentile on a narrower scale (SD 15) than on a wider one (SD 24), because the same point gap is more standard deviations from the mean. All figures computed from the normal-CDF model.
The takeaway: a bare IQ number means little without its scale. The widely quoted thresholds — 130 for "gifted", 100 for average — assume the SD 15 Wechsler scale, which is what most modern tests and online charts use. The calculator defaults to SD 15 and lets you switch to SD 16 or SD 24 if your score came from a Cattell-scaled test.
IQ classification table — what each range is called
Test publishers group scores into named bands. The table below is the standard Wechsler-style classification (the labels used by the WAIS), shown for the SD 15 scale. The calculator classifies by z-score rather than the raw number, so the band stays consistent even when you switch scales.
| IQ range (SD 15) | Classification | Approx. percentile | Share of people |
|---|---|---|---|
| 130 and above | Very Superior | 98th+ | ≈ 2% |
| 120–129 | Superior | 91st–97th | ≈ 7% |
| 110–119 | High Average | 75th–90th | ≈ 16% |
| 90–109 | Average | 25th–73rd | ≈ 50% |
| 80–89 | Low Average | 9th–24th | ≈ 16% |
| 70–79 | Borderline | 2nd–8th | ≈ 7% |
| 69 and below | Extremely Low | Below 2nd | ≈ 2% |
Standard Wechsler (WAIS-IV) classification labels. Ranges are for the SD 15 scale; the calculator applies the same bands by z-score on any scale. Labels vary slightly between publishers, but the thresholds (in standard deviations) do not.
IQ percentile chart (SD 15)
Most people want to see the whole curve, not just their own number. The chart below runs the model across common IQ scores on the SD 15 (Wechsler) scale and reports the percentile and rarity for each. Find the score nearest yours and read across.
| IQ (SD 15) | z-score | Percentile | Rarer than |
|---|---|---|---|
| 70 | −2.00 | 2nd | 1 in 44 (low end) |
| 80 | −1.33 | 9th | 1 in 11 (low end) |
| 90 | −0.67 | 25th | 1 in 4 (low end) |
| 100 | 0.00 | 50th | Exactly average |
| 110 | 0.67 | 75th | 1 in 4 |
| 115 | 1.00 | 84th | 1 in 6 |
| 120 | 1.33 | 91st | 1 in 11 |
| 130 | 2.00 | 98th | 1 in 44 |
| 140 | 2.67 | 99.6th | 1 in 261 |
| 145 | 3.00 | 99.9th | 1 in 741 |
Percentiles and rarity computed from the normal-distribution model (mean 100, SD 15). "Rarer than" uses the nearer tail — the share of people scoring at least this far from average in the same direction.
What is a good IQ percentile?
There is no single "good" IQ — by design, the most common result is an average one. About half of all scores fall between 90 and 109 (the 25th to 73rd percentile), so an entirely typical score is the statistical norm, not a shortfall. Roughly two-thirds of people score within one standard deviation of 100, between 85 and 115.
The widely cited landmarks are the 2nd-percentile tails at IQ 70 and 130. Many US school districts use 130 (the top ~2%) as a cut-off for gifted programs, and 70 is a common reference point in clinical assessment. But these are administrative thresholds, not bright lines about a person — someone at the 97th percentile and someone at the 98th are, for any practical purpose, indistinguishable.
IQ percentile and 'rarer than 1 in N'
The calculator also expresses your score as "rarer than 1 in N". This translates the percentile into a frequency: how many people you would expect to meet before finding one who scores at least as far from average, in the same direction, as you. It uses the nearer tail, so it works the same way for high and low scores.
| Percentile | Nearer tail | Rarer than |
|---|---|---|
| 50th | 50% | 1 in 2 (average) |
| 75th / 25th | 25% | 1 in 4 |
| 90th / 10th | 10% | 1 in 10 |
| 98th / 2nd | 2.3% | 1 in 44 |
| 99.9th / 0.1st | 0.13% | 1 in 741 |
Rarity is 1 ÷ (smaller tail). A score near the middle is, correctly, not rare at all — about 1 in 2 people are within a hair of the mean in one direction or the other.
This is the most honest way to read an extreme score. An IQ of 145 sounds dramatic, but the model just says about 1 in 740 people score that high — striking, but far from unique in a city. Because the normal curve is an approximation that gets shakier at the very edges, treat the rarity of any extreme score as a rough order of magnitude, not a precise count.
What an IQ percentile does and does not tell you
For the narrow question it answers — where a score ranks on the bell curve for its scale — the model is exact, because IQ scores are defined to be normally distributed. But an IQ score itself is a far narrower thing than the number suggests, and a few honest limits matter.
- It scores one test, not a person. IQ measures performance on a specific set of cognitive tasks. It is one narrow indicator, not a summary of intelligence, ability, or worth.
- The scale must match. A percentile is only valid for the standard deviation you select. Reading an SD 24 Cattell score as if it were SD 15 will badly overstate the percentile.
- Online tests are not clinical tests. Free internet IQ quizzes are not normed or proctored like the WAIS or Stanford-Binet, and their scores are far less reliable. Treat a casual result as entertainment.
- Single scores are noisy. Even a proper test has a margin of error; a score can shift several points on retest. The percentile is precise about the model, not about the underlying ability.
- The tails are approximate. The bell curve fits the middle of the range well but is only an approximation at the extremes, so a 99.9th-vs-99.99th distinction is more precise than any test can really support.
Data sources and methodology
IQ scores are normed to a mean of 100 with a standard deviation that depends on the test — 15 for the Wechsler scales (WAIS, WISC) and the modern Stanford-Binet, and 16 or 24 for the Cattell Culture Fair scales. The percentile is computed by converting the score to a z-score and applying the standard-normal cumulative distribution function, implemented via the Abramowitz & Stegun (7.1.26) error-function approximation. Classification follows the standard Wechsler (WAIS-IV) band labels, applied by z-score so they hold across scales.
IQ classification bands and scale conventions (Wechsler, Stanford-Binet, Cattell): IQ classification, Wikipedia.Wechsler Adult Intelligence Scale (WAIS-IV) score structure and classification labels.Frequently asked questions about the free iq percentile calculator
About this IQ percentile calculator
This IQ percentile calculator runs entirely in your browser — your score never leaves your device. It converts your IQ to a z-score against the normal curve for the scale you choose and reads off the percentile, updating instantly as you type.
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