IQ Percentile Calculator
Find the percentile for any IQ score. Enter a score and the scale it was reported on and this IQ percentile calculator shows the percent of people who score lower, the z-score, how rare the score is and its descriptive band. Example: an IQ of 130 on a standard deviation 15 scale is a z-score of 2.00 and the 97.7th percentile, about 1 in 44 people scoring higher. Remember that online results are estimates, not clinical IQ scores.
Type the problems from this lesson and check each step.
Between 20 and 200.
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How to use the IQ Percentile Calculator
- Type the IQ score from your report. Use a number between 20 and 200.
- Pick the scale. If your report says “standard score” with a mean of 100 and a standard deviation of 15, leave it on 15.
- Press Calculate to see the percentile, z-score, rarity and band, plus a lookup table for common scores.
- Read the note on limits before drawing conclusions: one score is an estimate with a margin of error.
Formula and method
IQ scores are built to follow a normal distribution with mean 100. The z-score is z = (IQ - 100) / SD and the percentile is the cumulative normal probability Phi(z) times 100. The share of people scoring at or above is 1 - Phi(z), and the rarity is its reciprocal.
Worked example: IQ 115 on SD 15 gives z = 1.00, Phi(1.00) = 0.8413, so the 84th percentile and about 1 in 6 people score higher.
What does an IQ percentile mean?
A percentile rank tells you the percentage of the reference group that scored below a given score. An IQ at the 84th percentile means about 84 out of 100 people in the norming sample scored lower. Percentiles are easier to explain than IQ points because they do not depend on which standard deviation a test publisher chose.
IQ percentile lookup table (SD 15)
| IQ | Percentile | Descriptive band |
|---|---|---|
| 70 | 2.3 | Very low |
| 80 | 9.1 | Low average |
| 85 | 15.9 | Low average |
| 90 | 25.2 | Average |
| 100 | 50.0 | Average |
| 110 | 74.8 | High average |
| 115 | 84.1 | High average |
| 120 | 90.9 | Very high |
| 130 | 97.7 | Extremely high |
| 145 | 99.9 | Extremely high |
The calculator above gives the exact value for any score, including decimals.
Why the scale (standard deviation) matters
The same raw label can mean different things on different scales. A score of 132 on an older Stanford-Binet scale with SD 16 equals z = 2.00, the same as 130 on SD 15 and 148 on a Cattell scale with SD 24. This calculator converts everything to a z-score first, so percentiles stay comparable. Our IQ score converter translates directly between scales.
Descriptive bands used by Wechsler scales
Wechsler publishers label ranges such as 90-109 as average, 110-119 as high average, 120-129 as very high and 130 and above as extremely high. These labels describe where a score falls in the distribution. They are not diagnoses. See the full IQ classification chart.
How accurate are very high or very low percentiles?
Accuracy falls toward the tails. Scores far from 100 are based on very few people in a norming sample, and test items often run out of difficulty, an effect called ceiling. Treat percentiles beyond roughly the 99.9th as theoretical. A confidence interval is more honest than a single number, so try the IQ confidence interval calculator.
Percentile versus percentage
A percentile is a rank, not a score out of 100. Scoring at the 90th percentile does not mean you answered 90 percent of questions correctly. It means you scored higher than 90 percent of the comparison group.
Limits and responsible use
Important: this is a statistics tool, not an IQ test. It converts a score you already have into a percentile and a descriptive band using a normal (bell-curve) model. Clinical IQ scores come only from a standardized test given and interpreted by a qualified psychologist, and online quizzes give estimates at best.
Do not use a percentile from this page to label yourself or others, to decide on schooling or employment, or to claim giftedness. If you need an evaluation, ask a licensed psychologist.
Frequently asked questions
What percentile is an IQ of 100?
The 50th percentile. By design the mean score of 100 splits the population in half.
What percentile is an IQ of 130?
About the 97.7th percentile on an SD 15 scale, which means roughly 1 person in 44 scores higher.
What IQ is the 99th percentile?
About 135 on an SD 15 scale (z = 2.33).
What IQ is the top 1 percent?
Roughly 135 or higher on SD 15, 137 on SD 16 and 156 on SD 24.
Is the percentile the same on every IQ test?
Only if the test is normed to the same mean and standard deviation. Always check which scale your score uses.
Can an online IQ test give a real percentile?
Online tests lack proper norming and supervised administration, so their percentiles are rough estimates. Use this calculator to understand a score, not to validate a quiz.
Why does the calculator stop at 200?
Normal-model rarity beyond that point has no practical meaning, since no norming sample contains enough people to measure it.
Sources
- Intelligence quotient (Wikipedia)
- IQ classification (Wikipedia)
- Standard score (Wikipedia)
- Normal distribution (Wikipedia)
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