ACT Composite Score Calculator

Background.

This ACT composite score calculator converts your four ACT section scores — English, Math, Reading, and Science — into your Composite score, using the current, official Enhanced ACT formula, while also showing the older four-section formula and your STEM score for comparison. Enter your four section scores (each on the standard 1-36 scale), and the calculator returns three numbers: the current Composite (rounded average of English, Math, and Reading only), the legacy Composite (rounded average of all four sections, including Science), and the STEM score (rounded average of Math and Science).

The reason this calculator asks for all four section scores and reports two different composites is that ACT itself changed how the Composite score is calculated, and the change is recent enough that it matters. According to ACT's own 2025 policy brief, "Interpreting Scores on the Enhanced ACT," the legacy ACT Composite score was the rounded average of the English, Math, Reading, and Science section scores — what ACT calls "EMRS." Starting with online national administrations in April 2025, and for every administration nationwide from September 2025 onward, ACT switched to reporting the Composite as the rounded average of just English, Math, and Reading — what ACT calls "EMR" — because the Science section became optional. A student who takes the Science section still receives a separate Science score and a STEM score (the average of Math and Science), but Science is no longer folded into the headline Composite number.

ACT's own research, summarized in that same brief, found that the enhanced EMR Composite and the legacy EMRS Composite concord almost point-for-point for most score ranges, and that the two versions predict college outcomes (first-year GPA, degree completion) at nearly identical rates. ACT explicitly states that institutions do not need to change how they interpret Composite scores because of this switch. Still, because the transition happened gradually — the graduating class of 2025 was reported almost entirely under the old EMRS formula, the class of 2026 is a mix of both, and only the class of 2027 onward is expected to be almost entirely EMR — a calculator that only computed one version would risk confusing a user checking an older score report against the new standard, or vice versa. This calculator sidesteps that confusion by computing both formulas from the same four inputs and clearly labeling which one is now the default.

The rounding step matters as much as the averaging step. ACT's own "Understanding Your Scores" page states the rule explicitly: the average is rounded to the nearest whole number, and a fraction of exactly one-half rounds up, not down and not to the nearest even number. That distinction is not academic — a class of scores that averages to exactly 24.5, for example, rounds up to 25 under ACT's rule, not down to 24, and a calculator that used a different rounding convention (some spreadsheet functions default to "round half to even" or "round half down") would occasionally disagree with an official ACT score report on exactly this kind of half-point case.

Because the ACT Composite, the STEM score, and the choice between old and new formulas all come directly from ACT's own published 2025 guidance rather than from an invented or approximated model, this calculator can state its formulas with confidence — the only genuinely uncertain part of ACT scoring, the conversion from raw number of correct answers to a 1-36 section score, is intentionally left out of scope here, because that conversion is equated per test form and ACT does not publish one universal table for it. This calculator starts from section scores you already have (from an official score report or a practice test's own scoring key) and combines them the way ACT itself combines them.

What is act composite score calculator?

The ACT Composite score is a single summary number, on the 1-36 scale, that combines a student's individual section scores. Historically (the "legacy" ACT), the Composite was the rounded average of four section scores: English, Math, Reading, and Science. Starting with the "Enhanced ACT" — phased in for online national test dates from April 2025 and applied to all administrations from September 2025 onward — the Composite is instead the rounded average of only three sections: English, Math, and Reading, because the Science section became optional. Students who do take the Science section still receive a separate Science score and a STEM score, defined by ACT as the average of the Science and Math section scores. All of this is documented directly in ACT's own 2025 publication "Interpreting Scores on the Enhanced ACT: Guidance for K-12 and Higher Education Institutions," which also specifies the rounding convention: averages are rounded to the nearest whole number, with an exact one-half fraction rounding up.

How to use this calculator.

1. 01Find your English, Math, Reading, and Science section scores from an official ACT score report or a practice test's scoring key (each is a whole number from 1 to 36).
2. 02Enter all four section scores into the calculator, even if your test administration did not include Science — if you skipped Science, enter your best estimate or leave the default so the STEM and legacy-composite figures can still be shown for reference.
3. 03Read the Composite score (current formula) — this is the number that matches your official score report if you tested from September 2025 onward.
4. 04Check the Composite score (legacy formula) if you are comparing against an older score report, or a sibling's or classmate's report from before the transition.
5. 05Check the STEM score if you took the Science section and want to see how your Math and Science performance combine.
6. 06Remember that this calculator combines section scores you already have — it does not convert raw number of questions correct into a 1-36 section score, because that conversion is equated per test form and ACT does not publish one universal table for it.

The formula.

ACT's own "Interpreting Scores on the Enhanced ACT" brief (2025) states the two formulas directly. The legacy Composite (EMRS) is the rounded average of all four section scores: (English + Math + Reading + Science) divided by 4. The enhanced Composite (EMR), the current standard for all administrations from September 2025 onward, drops Science from the average: (English + Math + Reading) divided by 3. Both are rounded to the nearest whole number using ACT's published rule: a fraction below one-half rounds down, and a fraction of exactly one-half or above rounds up.

Using the dossier's worked example — English 24, Math 27, Reading 22, Science 25 — the enhanced Composite is (24 + 27 + 22) divided by 3, which equals 73 divided by 3, or 24.333, rounding down to 24. The legacy Composite is (24 + 27 + 22 + 25) divided by 4, which equals 98 divided by 4, or exactly 24.5 — under ACT's round-half-up rule, this rounds up to 25, one point higher than the enhanced Composite for the identical set of section scores. This is precisely the kind of case ACT's own guidance flags: dropping Science from the average changes not just which sections count, but occasionally the rounded result itself, even when the underlying section scores are unchanged. The STEM score, defined by ACT as the average of Math and Science, is (27 + 25) divided by 2, which equals 26 exactly, needing no rounding in this case.

ACT's research (cited in the same brief) found that the enhanced and legacy Composite scores correlate at 0.99 and concord point-for-point for nearly all Composite scores above 13, meaning the switch rarely changes a student's Composite by more than a point or two — but as the worked example shows, it can occasionally change it by exactly one point, which matters for programs, scholarships, or admissions thresholds set at a specific Composite cutoff.

A worked example.

Frequently asked questions.

References& sources.

1. [1]ACT Education Corp (2025). "Interpreting Scores on the Enhanced ACT: Guidance for K-12 and Higher Education Institutions." Source of the EMR/EMRS Composite formulas, the STEM score definition, and the transition timeline.
2. [2]ACT — Understanding Your Scores. Official page stating the round-half-up rounding rule for the Composite score.
3. [3]ACT — ACT Test Enhancements for Higher Education. Official overview of the Enhanced ACT changes, including the optional Science section.
4. [4]ACT and PreACT Changes and Enhancements for K-12 Educators. Official K-12-facing summary of the Enhanced ACT rollout timeline.
5. [5]U.S. Department of Education, National Center for Education Statistics (NCES) — Handbook of Survey Methods. General federal reference on standardized test score reporting conventions.