Scores
IQ Calculator: Turn a Score Into a Percentile
This IQ calculator turns a score into a percentile and a percentile into a score. It also converts between test scales. It uses the same math as our test and our score pages. It needs a score from a real test to mean anything.
- Percentile: 97.72, the share of people who score lower.
- Rarity: about 1 in 44 people score this high or higher.
- Labels: Extremely High in WISC-V wording; Very Superior in traditional WAIS-IV wording.
- Same point on other scales: about 132 with SD 16, about 148 with SD 24.
How do you calculate IQ from a percentile?
To calculate IQ from a percentile, find its z value, multiply by 15 and add 100. The z value says how far a point sits from the middle, in standard deviations. The calculator does this for you. The steps are simple.
IQ = 100 + 15 × z
- Start with the percentile, for example 98.
- Find the z value for it: 2.054.
- Multiply by 15 and add 100: the result is 130.8.
That is why people say the 98th percentile is “about 130”. Mensa’s own psychologist calls it two standard deviations above the mean, rounded off. Scores above that line are rare. Our page on what IQ is considered genius explains the popular cutoffs.
How is an IQ score calculated on real tests?
A real test turns your raw score into a standard score. It does this by comparing you with a norming sample. That is a large group who took the test first to set its scale. Their average score becomes 100.
In Wechsler’s method, someone who scores at the mean of their age group gets exactly 100. The spread is then set so that one standard deviation is usually 15 or 16 points. This is called a deviation IQ.
So there is no formula you can run at home on your raw answers. Turning answers into an IQ needs the test’s norms. Our methodology shows how our own test does it. It also explains why our norms are still provisional.
How do you convert IQ scores between tests?
You convert an IQ score between tests through its rank. The same percentile gets a different number on a scale with a different spread. Most modern tests use an SD of 15. Older Stanford-Binet forms and many school tests use 16. The Cattell test and the old Raven’s Advanced Progressive Matrices use 24.
new score = 100 + new SD × (old score - 100) / old SD
Here is the classic example. A 130 on an SD 15 test is about 132 with SD 16 and about 148 with SD 24. Those are exactly the lines Mensa lists for those scales. The Mensa IQ test guide shows every accepted test.
Converting never makes a score more precise. It only changes the number that stands for the same rank.
What is ratio IQ, and why is it not used for adults?
Ratio IQ is mental age divided by real age, times 100, and it only works for children. The psychologist William Stern proposed the division. Terman later multiplied the result by 100 for the Stanford-Binet test.
A 10-year-old who solves problems like an average 12-year-old gets 120. The method works only while older age generally means better abilities. That holds in childhood, so it fails for adults. Modern tests use the deviation IQ instead. It compares you with people of your own age.
Very old claims of extreme IQs are hard to compare with modern scores. Our page on the highest IQ score explains why.
What does an IQ percentile mean?
An IQ percentile is the share of people who score lower than you. A 115 is at the 84.13th percentile. A 130 is at the 97.72nd percentile, and about 1 in 44 people score that high or higher.
The average score, 100, sits at the 50th percentile by design. Read what a 100 IQ means. You can also see why the average IQ stays at 100. Every band, with its share of people, is on the IQ scale.
A percentile is not a test mark. A percentile of 90 does not mean 90% of answers were right.
Can an IQ calculator tell you your IQ?
No. An IQ calculator converts a score you already have. It cannot measure you. To get a score, you need a test with norms.
Our free IQ test gives an estimate in one sitting, with 30 questions and a range around the result. For a formal score, a psychologist or an approved supervised test is the route.
FAQ
How is IQ calculated?
IQ is calculated by comparing your raw score with a norming sample. The sample’s average becomes 100, and each standard deviation is usually 15 points. A score of 115 means one standard deviation above the average.
What percentile is a 130 IQ?
A 130 IQ is at the 97.72nd percentile. About 1 in 44 people score that high or higher. See what a 130 IQ means for the full picture.
What IQ score is the 99th percentile?
The 99th percentile is an IQ of about 134.9 on an SD 15 test. With SD 16 it is about 137.2.
What IQ score is the 90th percentile?
The 90th percentile is an IQ of about 119.2 on an SD 15 test.
What IQ score is the 99.9th percentile?
The 99.9th percentile is an IQ of about 146.4 on an SD 15 test. That is only 1 person in 1,000.
Why do different IQ tests give different numbers?
Different tests give different numbers for two reasons. Some use a different SD, so the same rank gets another number. And every score has some error. A second test can land a little higher or lower. Our guide are IQ tests accurate explains the error.
Can you use a calculator on an IQ test?
Rules differ by test, so ask whoever gives it. On our test, the number questions use small whole numbers, so a calculator is not needed.