On each major subscale of the SAT, scores range from 200 to 800. Most sources converting SAT scores to IQ are based on one’s combined score on the reading and math subscales and thus range from 400 to 1600. But current forms of the SAT actually have three subscales (reading + math + writing) so it’s useful to know how the combined score on all three subscales converts to IQ, since many sources only provide total scores from all three subscales. These ranges from 600 to 2400.
In 2013, the average college bound high school senior had an SAT score of 1499 out of 2400 (reading + math + writing) and a score of 1008 out of 1600 (reading + math). An equation I created shows that since 1995, a 1008 out of 1600 on the SAT is somewhat equivalent to an IQ of 108; thus a score of 1499 out of 2400 is also roughly equal to IQ 108. Now of the 1,660,047 people who took the SAT in 2013, only 494 scored a perfect 2400. That’s one out of every 3,360 people. However only about 35% of American 17 year olds take the SAT, and scholars Charles Murray and Ron Hoeflin have argued that the higher the ability, the greater the odds of taking the test. Thus among 17 year-old Americans capable of scoring 2400 on the SAT, virtually 100% actually do so. Thus one out of 3,360 becomes one out of 9,600, because virtually none of the people who didn’t take the test were capable of scoring 2400.
If the IQs of Americans are forced to fit a bell curve with a mean of 100 and a standard deviation of 15, a score at the one in 9,600 level is assigned an IQ of about 156. Thus we have two data points:
SAT 2400 out of 2400 = IQ 156
SAT 1499 out of 2400 = IQ 108
From here we can create the following linear equation converting SAT scores to IQ:
IQ = 28.142 + 0.05327 (SAT score)
Of course it should be noted that these IQs are on a scale where the American mean is set at 100 and the SD set at 15. Increasingly in the technical literature, IQs are scored relative to the white distribution, not the American distribution.
To convert from American IQ scores to white IQ scores apply this formula:
White IQ = [(American IQ – 103)/14.5](15) + 100
The advantage of using white norms is they provide a more stable reference for anchoring IQ that is much less influenced by demographic changes.