IQ percentile & rarity calculator
Enter any IQ score — from this test or any other — to get its percentile rank and population rarity. Or go the other way: enter a percentile to see the equivalent IQ score. Uses the exact standard deviation-IQ model (mean 100, SD 15) described on our scoring page, computed live in your browser. Nothing is sent anywhere.
IQ score → percentile
Standard deviation-IQ scale, mean 100, SD 15.
Percentile → IQ score
Inverse of the same normal-distribution model.
How this is computed
Deviation IQ scores are constructed so that, on the norming population, scores follow a normal (bell-curve) distribution with mean 100 and standard deviation 15 — the same convention used by clinical batteries like the WAIS-IV and Stanford-Binet 5, and the one this site's own scoring page uses. Given that model, a score's percentile rank is just the area under the curve below it, and "rarity" is 1 ÷ (fraction of people scoring at or above it). This calculator runs that math (a standard normal CDF and its inverse) directly in your browser — there is no server round-trip and no data collection.
This is a mathematical conversion, not a new measurement: it tells you what a given score implies under the standard model, not how precisely any particular test measured you. Real tests carry measurement error the calculator can't see — see Percentile vs. IQ Score: Reading the Numbers for how to interpret a real result responsibly, and the IQ band guide for what each range means in plain language.