The most widely used IQ tests
There is no single 'the IQ test'. Several distinct instruments are in professional use, and they differ in what they sample and who they are built for.
WAIS — Wechsler Adult Intelligence Scale
The most widely used adult battery in clinical practice. It reports four index scores — verbal comprehension, perceptual reasoning, working memory and processing speed — alongside a full-scale score. Administered one-to-one, it takes 60 to 90 minutes.
WISC — the children's version
The same design adapted for ages 6 to 16. It is the standard instrument behind school placement decisions and learning-difficulty assessments in much of the world.
Stanford-Binet
The oldest line still in use, descended directly from Binet's original 1905 work. It covers a very wide age range and remains common in gifted identification, partly because it discriminates well at the high end.
Raven's Progressive Matrices
Purely non-verbal: every item is a visual matrix with one piece missing. Because it needs no reading and no cultural knowledge, it travels across languages better than verbal batteries, and it is the format most online tests borrow from.
Cattell Culture Fair
Explicitly designed to minimise the effect of schooling and language. Mensa accepts it as a qualifying test in several countries.
How they compare
- Broadest picture, clinical use: WAIS or WISC, supervised, paid, an hour or more.
- Fairest across languages: Raven's or Cattell.
- Best discrimination at the very high end: Stanford-Binet.
- Quick self-assessment: online tests built on matrix and sequence items — useful for practice and curiosity, not for decisions.
TopIQ sits in that last group. It samples the same ability areas as the professional batteries and reports them separately, but it is unsupervised, and no unsupervised test should be used where a formal assessment is required.