ACT Score Glossary: Composite, STEM Score & Concordance
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Full bio →Why This Vocabulary Matters
The 2025 Enhanced ACT redesign introduced new terminology alongside its structural changes. This glossary defines the terms behind a result from the ACT score calculator.
ACT Composite
The ACT Composite is the single headline score (1-36) most colleges reference, calculated as the average of your section scores. Under the current Enhanced ACT, per ACT’s own materials, Composite averages English, Math, and Reading only. Under the Legacy ACT (pre-2025), it averaged all four sections including Science.
Section Score
A section score is the individual 1-36 score for one ACT subject — English, Math, Reading, or (optional) Science. Section scores are the building blocks the Composite is calculated from.
STEM Score
The STEM Score is a score introduced with the Enhanced ACT that averages Math and Science section scores, reported separately from the Composite. It only appears on a score report if the optional Science section was taken.
Enhanced ACT
The Enhanced ACT is the current, redesigned version of the test, rolled out online starting April 2025 and on paper starting September 2025. Per ACT’s own site, the biggest structural change is that Science became optional and was removed from the Composite formula.
Legacy ACT
The Legacy ACT refers to the test format used before the 2025 redesign — a four-section Composite average including Science as a required, scored component. Anyone who tested before the rollout has a Legacy-format score report.
ACT/SAT Concordance
Concordance is a statistically derived table linking ACT Composite scores to comparable SAT Total scores, based on score distributions from a shared population of students who took both exams. The current official version is the 2018 ACT/SAT Concordance Tables. See using ACT/SAT concordance for scholarships for how this gets applied practically.
Comparable Score Band
A comparable score band is the range of SAT scores officially considered statistically equivalent to a given ACT Composite in the concordance tables — for example, an ACT Composite of 27 concords to an SAT Total of 1280, with a published comparable band of 1260-1290, reflecting that concordance is a statistical relationship, not an exact one-to-one mapping.
Superscore
A superscore combines a student’s best individual section scores across multiple test dates into a new, recalculated Composite — a practice some (not all) colleges accept. It’s distinct from the Composite reported on any single test date’s official score report.
Round Half Up (ACT’s Rounding Rule)
Round half up is ACT’s specific rounding convention for the Composite: a raw average fraction below 0.5 rounds down, and 0.5 or above rounds up. This differs from “round half to even” (banker’s rounding), used in some other contexts — a raw average of exactly 25.5 becomes 26 under ACT’s rule.
Putting the Terms Together
Once you know the difference between the Enhanced and Legacy Composite formulas, and what concordance actually represents, a result from the ACT score calculator is much easier to interpret correctly. See common ACT score mistakes for the errors that most often trip students up.