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ACT Score Calculator: Composite Score & Percentile

Calculate your official ACT Composite and STEM scores from section scores with national percentile ranking.

Quick Answer:The ACT Composite score is the unweighted average of the four test section scores (English, Math, Reading, Science), rounded to the nearest whole integer.

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How to Use the ACT Score Calculator & Composite Estimator

1Enter your scaled score (1–36) for English.
2Enter your scaled score (1–36) for Math.
3Enter your scaled score (1–36) for Reading.
4Enter your scaled score (1–36) for Science.
5View your official rounded Composite ACT score, STEM score, and national percentile.

Formula & How It Works

Official ACT Composite Formula

Composite = Round((English + Math + Reading + Science) / 4)

Sum all four section scores, divide by 4, and round to the nearest integer. If the decimal average is .5 or higher, round up.

Worked Examples

Competitive University Target Score

Input: English = 34, Math = 32, Reading = 33, Science = 30

Explanation: (34 + 32 + 33 + 30) / 4 = 129 / 4 = 32.25 → Rounds down to 32.

Result: Composite: 32 (Average: 32.25, 97th Percentile)

Beneficial ACT Rounding Example

Input: English = 29, Math = 31, Reading = 32, Science = 31

Explanation: (29 + 31 + 32 + 31) / 4 = 123 / 4 = 30.75 → Rounds up to 31.

Result: Composite: 31 (Average: 30.75, 95th Percentile)

Exact 0.5 Boundary Case

Input: English = 28, Math = 30, Reading = 29, Science = 27

Explanation: 114 / 4 = 28.50 → Official ACT rules round .5 up to 29.

Result: Composite: 29 (Average: 28.5, 90th Percentile)

Frequently Asked Questions

How is the ACT score rounded?▼

The ACT calculates the exact arithmetic average of your four section scores. If the decimal is .5 or higher (such as 30.5 or 30.75), it rounds up to the next whole number (31). If it is below .5 (such as 30.25), it rounds down (30).

What is an ACT superscore?▼

An ACT superscore takes the highest section score from any test attempt and recalculates a new composite average.

What is a good ACT score?▼

The national average ACT composite is approximately 20 to 21. Scores above 28 are in the top 12% nationally, while scores of 32+ place you in the top 3%.

Does the Writing test affect the composite score?▼

No. The optional Writing test produces a separate score from 2 to 12 and does not factor into the 1–36 composite score.

What is the STEM score on the ACT?▼

The STEM score is the average of your Math and Science section scores, rounded to the nearest whole integer.

Is this tool accurate to official testing rules?▼

Yes, it implements the official ACT rounding guidelines and concordance percentiles.

Quick Reference & Conversion Table

ACT Composite	National Percentile	SAT Equivalent Range
36	99th+	1570 – 1600
34	99th	1490 – 1520
32	97th	1420 – 1440
30	93rd	1360 – 1380
28	88th	1300 – 1320
24	74th	1160 – 1190
20	52nd	1030 – 1050

⚠️ Common Pitfalls to Avoid

•Assuming raw questions correct are scaled scores (raw scores must first be mapped through the specific test's official curve).
•Thinking the optional Writing essay score affects the composite score (it does not).
•Rounding 27.25 up to 28 (fractions below .50 round down to the nearest whole number).

💡 Practical Real-World Uses

•College admissions planning and university scholarship qualification.
•Standardized test prep diagnostics after practice exams.
•Assessing superscore potential across multiple ACT test administrations.

ACT Composite vs ACT STEM Score

✓Composite reflects general academic readiness across all 4 subjects (English, Math, Reading, Science).
✓STEM Score is the average of Math and Science specifically, used by engineering and science programs.

Last reviewed & updated: 2026-11-01

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