Convert an ACT score to an estimated IQ-style score using standard-score rescaling, with an ACT to IQ chart. ACT is an achievement test, not an IQ test.

ACT is an achievement test, not an IQ test. This rescales your score assuming ACT mean 20.8 and SD 5.2.

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Illustrative ACT Score Rescaling Formula

The following formula produces an illustrative rescaled score by matching standardized scores (z-scores). The assumed ACT mean 20.8 and standard deviation 5.2 are retained from the supplied formula, not asserted to be current norms. This is not a validated IQ conversion.

IQeq ≈ 100 + 15 × (ACT - 20.8) / (5.2)

Variables:

  • IQeq is an illustrative score on a scale with mean 100 and standard deviation 15, not an IQ result
  • ACT is the ACT Composite score (typically 1–36)

To reproduce the rescaling, compute z using the assumed ACT mean 20.8 and standard deviation 5.2, then calculate 100 + 15z. Matching these scales does not establish that the tests measure the same trait.

Illustrative ACT Score Rescaling Table (assumed z-score mapping)
ACT Score Illustrative rescaled score
1068.8
1274.6
1480.4
1583.3
1686.2
1891.9
2097.7
21100.6
22103.5
24109.2
25112.1
26115.0
28120.8
30126.5
31129.4
32132.3
33135.2
34138.1
35141.0
36143.8
Method used: IQeq ≈ 100 + 15 × (ACT − 20.8) ÷ 5.2 (assumes ACT mean 20.8, SD 5.2; IQ mean 100, SD 15). Inverse: ACT ≈ (((IQ − 100) ÷ 15) × 5.2) + 20.8. ACT Composite range: 1–36.

How to Rescale an ACT Score?

The following steps reproduce the illustrative standardized-score calculation; they do not estimate IQ.

  1. First, determine the ACT Composite score (typically 1–36).
  2. Compute the ACT z-score: z = (ACT − 20.8) ÷ 5.2 (using the stated assumptions).
  3. Convert to the illustrative 100/15 scale: IQeq ≈ 100 + 15 × z.
  4. The obtained value is an illustrative rescaling, not an IQ prediction. Do not use it for admissions, employment or diagnosis.
  5. After inserting the ACT score and performing the calculations, you can check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

ACT Composite score = 25 (illustrative rescaled score ≈ 112.1)