How is a child IQ test different from an adult one?

Children's IQ tests are structured similarly to adult tests but use age-appropriate items and are normed against same-age peers. The most widely used clinical instruments are the Wechsler Intelligence Scale for Children (WISC-V) for ages 6 through 16, the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-IV) for ages 2 through 7, and the Stanford-Binet 5 (SB5), which spans ages 2 through 90. Childhood IQ is less stable than adult IQ — the test-retest correlation across long intervals is lower because childhood cognitive development is rapid and uneven. Most clinicians weight a childhood IQ result less heavily than an adult one when interpreting it.

This question comes up frequently from users of free online IQ tests and from people considering whether to pursue a clinical evaluation. The full answer depends on context — what the score will be used for, how recently the test was administered, and what other information is available. The brief answer above captures the broad consensus from the published research literature; the linked deep-dive articles cover the underlying evidence in more detail.

Related considerations include the standard error of measurement on the relevant test, the population the test was normed against, and the specific cognitive abilities the test samples. A score is much more informative when interpreted alongside these contextual variables than when reported as a bare number.

If this answer raises further questions, see the related FAQ entries listed in the sidebar and the longer-form articles on the same topic in the article library. The site is designed to provide layered depth: the FAQ entries offer concise answers, the deep-dive articles offer the underlying research, and the score-interpretation pages tie the abstract concepts to specific result bands.