Convert IQ ↔ ACT
How the conversion works
IQ and ACT scores are normalised on bell-curve distributions. The conversion maps a person's standing in one distribution to the equivalent standing in the other.
- IQ: mean 100, standard deviation 15.
- ACT composite: mean ≈ 21, standard deviation ≈ 5, based on ACT national score reports.
IQ-equivalent = (target − meantarget) / SDtarget × 15 + 100
target-equivalent = (IQ − 100) / 15 × SDtarget + meantarget
Common IQ ↔ ACT reference table
| IQ | ACT | Percentile |
|---|---|---|
| 85 | 16 | ~16th |
| 90 | 18 | ~25th |
| 100 | 21 | ~50th |
| 110 | 24 | ~75th |
| 120 | 27 | ~91st |
| 130 | 30 | ~98th |
| 140 | 33 | ~99.6th |
Important caveats
- The ACT measures developed academic skills; IQ measures general cognitive ability. They correlate around 0.7, not 1.0, so an individual can plausibly score higher on one than the other.
- Extreme-tail conversions are less reliable because both tests have fewer calibration cases there.
- No score entered here is stored, submitted, or connected to an account.
What is the ACT composite score, and how does it relate to IQ?
The ACT composite score is a college admissions test result reported on a 1 to 36 scale, calculated as the rounded average of four section scores in English, Math, Reading, and Science. Because the ACT is a timed, broad measure of learned reasoning and problem solving, it correlates strongly with general cognitive ability, with research placing the relationship between standardized college tests and measured IQ at roughly 0.7 to 0.8. That means a high ACT composite reliably tracks a high IQ, and an ACT score can be mapped to an approximate IQ-equivalent percentile.
The ACT composite ranges from a minimum of 1 to a maximum of 36, with the national average sitting around 19 to 21 in recent years. Each of the four sections (English, Math, Reading, Science) is scored from 1 to 36, and the composite is the average of those four rounded to the nearest whole number, so the composite carries the same 1 to 36 range. The test is administered by ACT, Inc. and is accepted interchangeably with the SAT by U.S. colleges. The link to IQ works through two steps: the ACT correlates highly with the general intelligence factor known as g, and official ACT-SAT concordance tables let you translate an ACT composite into an equivalent SAT score and percentile, from which an IQ-equivalent percentile can be estimated. This converter is used by students, parents, and the gifted and high-IQ community to get a fast, defensible IQ estimate from a score they already have.
How the ACT composite maps to an IQ-equivalent
The mapping is percentile based, not a direct formula. The ACT composite is converted to a national percentile rank, that percentile is matched to the same percentile on the IQ bell curve, and the result is read off as a standard IQ score where the mean is 100 and the standard deviation is 15.
Here is the core logic in three steps:
- Find the percentile for your ACT composite using ACT national norms.
- Match that percentile to the IQ distribution (mean 100, SD 15).
- Read the IQ score that sits at that same percentile.
For example, a composite around the national average of roughly 20 lands near the 50th percentile, which corresponds to an IQ near 100. Higher composites pull the IQ estimate up steeply because the top of the ACT scale compresses the most able test takers into a narrow band of scores.
Why the ACT is a strong proxy for general intelligence
The ACT is timed, broad, and demanding across verbal, quantitative, and reasoning domains, which is exactly the profile that loads heavily on the general intelligence factor g. Peer reviewed work on standardized admissions tests, including the well known analysis by Frey and Detterman on the SAT, reports correlations with measured IQ in the range of about 0.7 to 0.8, and the ACT behaves similarly because it measures the same underlying construct.
Three features make the ACT a reliable proxy:
- It samples multiple cognitive domains (English, Math, Reading, Science) rather than one narrow skill.
- It is administered under standardized timed conditions, which taps reasoning speed and working memory.
- It is normed on a very large national population, giving stable percentile estimates.
The correlation is strong but not perfect, so an ACT based IQ estimate is best read as an informed approximation rather than a clinical diagnosis.
The ACT-SAT concordance bridge
Because both tests measure the same general ability, ACT, Inc. and the College Board publish official ACT-SAT concordance tables that let you cross map a composite to an equivalent SAT total. This matters for IQ estimation because much of the published research on test-to-IQ correlation was built on the SAT, so concordance lets ACT scores inherit that same evidence base.
A simplified view of the bridge:
These figures follow the published concordance ranges and national percentile norms. Use the converter above for the precise IQ-equivalent at your exact composite, since the relationship is nonlinear at the top and bottom of the scale.
Frequently asked questions
What IQ does a 36 ACT score equal?
A perfect 36 ACT composite sits at roughly the 99th percentile or above of all test takers. Matched to the IQ bell curve, that corresponds to an estimated IQ in the area of 135 or higher. Because the very top of the ACT scale compresses many extremely able students into a single score, a 36 represents a wide band of elite ability rather than one exact IQ point, so treat 135 plus as a conservative floor for this score.
Is the ACT a good predictor of IQ?
Yes. Standardized college tests like the ACT correlate with measured IQ at roughly 0.7 to 0.8, which is one of the strongest real-world predictors of general intelligence available outside a formal IQ test. The ACT samples verbal, quantitative, and reasoning ability under timed conditions, which is precisely what loads on the general intelligence factor g. It is a strong proxy, though not a clinical substitute for a proctored IQ assessment.
What is the average ACT score and what IQ does it represent?
The national average ACT composite has been around 19 to 21 in recent years, which falls near the 50th percentile. That percentile corresponds to an IQ near 100, the midpoint of the standard IQ scale where the mean is 100 and the standard deviation is 15. In short, an average ACT score maps to an average IQ.
How accurate is converting an ACT score to IQ?
The conversion is a strong statistical estimate, not a diagnosis. It relies on the high correlation between the ACT and g and on official percentile norms, so it reliably places you in the correct IQ range. The margin of error widens at the extreme high and low ends of the scale, where scores compress, so read the output as an approximate IQ-equivalent rather than an exact number.
How does the converter turn my ACT score into an IQ?
It uses a percentile bridge. Your ACT composite is converted to a national percentile rank, that percentile is matched to the same point on the IQ distribution (mean 100, SD 15), and the IQ score at that percentile is returned. Because both the ACT and IQ are normed on large populations, lining up their percentiles gives a defensible IQ-equivalent for any composite from 1 to 36.
Can I convert my ACT score to an SAT score and then to IQ?
Yes, and that is exactly how the concordance bridge works. Official ACT-SAT concordance tables map your composite to an equivalent SAT total, and from there to a percentile and IQ-equivalent. This is useful because much of the published test-to-IQ research was built on the SAT, so concordance lets your ACT score draw on that same evidence base.
Related tools
IQ percentile calculator · IQ to SAT converter · IQ to GRE converter · IQ score chart
Cite this converter
Editorial content and curation are released under CC BY-SA 4.0. This converter is part of the What's Your IQ educational resources.