How does IQ predict academic performance?

IQ is one of the strongest single predictors of academic performance, with correlations of approximately 0.5 with school grades, 0.7 with standardized test scores, and 0.5 with years of schooling completed. The correlation is stronger for grades in subjects that emphasize abstract reasoning (mathematics, science) and weaker for subjects that emphasize execution (art, physical education). The correlation also strengthens at higher levels of academic difficulty: IQ predicts grades in graduate school more strongly than grades in elementary school. Importantly, IQ accounts for less than half the variance in academic performance even at the strongest correlations; conscientiousness, motivation, schooling quality, and family support account for substantial additional variance.

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.