IQ Score Converter

How IQ Scale Conversion Works

Different IQ tests report scores on different scales. The Wechsler tests (WAIS-IV, WISC-V) and the modern Stanford-Binet 5 both use a mean of 100 and standard deviation of 15, but the Cattell Culture Fair test uses a standard deviation of 24. This makes direct comparison misleading without conversion.

The converter uses z-score transformation: it first calculates how many standard deviations your score is from the mean on the source scale, then maps that position onto each target scale. For IQ-to-IQ conversions this is mathematically precise. For standardized test equivalents (SAT, ACT, GRE), the conversions are approximate estimates based on published correlation data.

Understanding the Wechsler vs. Cattell Difference

The most common source of confusion in IQ scores is the difference between the Wechsler scale (SD = 15) and the Cattell scale (SD = 24). A Cattell score of 148 sounds dramatically high, but it is equivalent to a Wechsler score of 130; both represent the 98th percentile. Online IQ tests sometimes report on the Cattell scale without making this clear, which can lead to inflated expectations.

For a deeper comparison of IQ testing systems, see our guide to WAIS vs. Stanford-Binet vs. online IQ tests.

SAT, ACT, and GRE as IQ Proxies

Standardized academic tests correlate with IQ but are not interchangeable with it. Research shows correlations of approximately 0.80–0.85 for the SAT, 0.75–0.80 for the ACT, and somewhat lower for the GRE (which draws from a pre-selected, above-average population). These conversions should be treated as rough estimates, not precise equivalencies.

For more on this topic, see our article on LSAT, MCAT, and GRE IQ correlations.

Important Caveats About Score Conversion

Once you have converted your score, explore what it means with our IQ Score Meaning tool, or see where it falls on the bell curve with the IQ Standard Deviation Calculator. You can also check your exact percentile ranking.

• IQ-to-IQ conversions (Wechsler, Stanford-Binet, Cattell) are mathematically precise when both tests measure the same construct.
• Test score equivalents (SAT, ACT, GRE) are statistical approximations. The SAT measures learned academic skills in addition to general cognitive ability.
• Score capping: when a conversion falls outside a scale's valid range, it is capped to the nearest boundary. Capped scores are marked with an asterisk (*).
• Mensa eligibility requires the top 2% on a proctored, recognized IQ test, not an online converter. This tool shows whether your score falls in the qualifying range.

Frequently Asked Questions