Reference
IQ charts and reference tables
The numbers people come looking for, with the working shown. Every table on these pages is generated from the normal distribution and states what it assumes.
Reference tables about IQ circulate endlessly and almost never carry a source or a date. These are built from the scale itself, which means you can check them, and the ones that rest on outside data say whose data and what is wrong with it.
Everything in this section
IQ percentile chart
Every score from 40 to 160 converted to a percentile and a rarity figure, plus a calculator for anything in between.
Read more →IQ classification ranges
The current bands, the share of the population in each, and a hundred years of the labels being rewritten.
Read more →What is the average IQ?
Why the answer is 100 by construction, what the average hides, and the century of rising raw scores underneath it.
Read more →What is a good IQ score?
Six versions of the question — statistical, academic, professional, Mensa, gifted, personal — each with its own threshold.
Read more →Average IQ by age
Why every age group averages 100, what really changes across a lifetime, and why old comparison tables mislead.
Read more →Average IQ by country
The dataset everyone quotes, published with the sampling problems that are usually left out.
Read more →Start with your own result
Ten questions, no sign-up, and a band rather than an invented number.