Each ACT point is worth about 2.5 IQ points
Bar height is the share of takers at each composite under a normal model (mean 19.5, SD 5.9 for the class of 2023 per ACT's national profile report). Click a bar to load it. The top bar is a ceiling: everyone above it is pooled at 36.
A 28 in a test-everyone state is not a 28 where only applicants sit it
Some states give the ACT to every junior; in others only students aiming at selective colleges take it. State averages differ by several points mainly because of who is in the room. Pick a pool to see your composite re-ranked.
Mostly, and less than a straight rank match implies
Koenig, Frey and Detterman (2008) followed the method of the earlier SAT study: in a national longitudinal sample with both ACT scores and the ASVAB, the ACT correlated about .77 with a general factor. That sample was 1,075 people from the 1979 National Longitudinal Survey of Youth. A second sample of 149 students who took Raven's Advanced Progressive Matrices showed a correlation of .61.
A correlation of .77 means the tests share a little under 60% of their variance (.77² ≈ .59). The rest is coursework, preparation, reading speed, motivation on the day, and measurement error in both.
The official concordance, ACT 15 to 36
ACT composite (top) and concordant SAT total (bottom), from the official 2018 ACT/College Board concordance (Table A2, single-score values; checked Oct 2026). ACT's 2025 guidance says this table can still be used with the three-section enhanced ACT; no newer joint study exists. Concordance pairs scores with equal percentile among students who took both tests, a different group from either test's full pool.
- Koenig, K. A., Frey, M. C., & Detterman, D. K. (2008). ACT and general cognitive ability. Intelligence, 36(2), 153–160.
- ACT, Inc. (2023). The ACT Profile Report: National, Graduating Class 2023. National average composite about 19.5.
- ACT, Inc. & College Board (2018). Guide to the 2018 ACT/SAT Concordance.
- ACT, Inc. (2024). Announcement of the enhanced ACT: shorter test, Science optional, composite from English, Math and Reading.
- Frey, M. C., & Detterman, D. K. (2004). Scholastic Assessment or g? Psychological Science, 15(6), 373–378.