What Is an IQ Test? Types, How They Work, and Choosing a Free Online Test

Search for 'IQ test' and you'll find everything from formal psychological assessments to two-minute quiz games. This article sorts out the types of IQ tests, how they work, and what to look for when choosing one online.

The main types of IQ test

IQ tests fall into three broad categories: (1) individually administered tests given one-on-one by a psychologist (WAIS, Binet-type scales), (2) group tests used in schools and hiring, and (3) casual online tests. Only category (1) can be used for medical or educational determinations; online tests are for getting a rough estimate.

Question formats center on figures

Figure-based problems (matrix reasoning, number sequences, classification) don't depend on language or acquired knowledge, which makes them resistant to cultural and educational bias — and that's why they form the core of most IQ tests. We publish tips for the classic Raven-style matrices and sample problems by domain.

Four checkpoints for a free online IQ test

(1) Is the scoring method disclosed (simple correct-count, or IRT scoring that weighs item difficulty)? (2) Are there enough questions and time (a handful of items means huge measurement error)? (3) Are results returned on the standard scale of mean 100, SD 15? (4) Does the site hand everyone 'Your IQ is 145!' to bait shares? We examine this in depth in how accurate are free IQ tests.

How BrainRank's IQ test works

BrainRank's free IQ test scores 20 questions across four domains — based on the rule taxonomy of Raven's matrices (Carpenter et al., 1990) — with item response theory (IRT), returning your estimated IQ, deviation score, and top percentile. The design is documented in our methodology. About 10 minutes, no registration.