From the beginning Oprah was black and brilliant.

A few readers think I’m crazy for thinking Oprah could have an IQ around 140. For some dismiss her as just another mediocre celebrity entertaining the unwashed masses. And 140 is a truly astonishing figure, when one considers that the average white U.S. college graduate has an IQ around 111, the average white PhD has an IQ around 123 and the average U.S. president has an IQ around 130. Many find it unimaginable that overweight black woman who entertains housewives could be so much smarter than all those people.

But the first thing to keep in mind is that Oprah’s not just an entertainer, she’s a billionaire, with a B, and she’s a billionaire several times over. Think about how hard it is to go out and make a million U.S. dollars, and then imagine doing so 3000 times, and keeping every penny, and you have a sense of just much genius is required. The following chart is a very rough approximation for the relationship between money and IQ in America. It’s hard to pin down exact numbers, but a good rule of thumb is that Americans tend to be close to ten IQ points smarter than Americans who earn ten times less than they do, and they tend to be ten IQ points dumber than those who earn ten times more:

Homeless people (three figure income earners): Average IQ 76

The working poor (four figure income earners): Average IQ 86

Average Americans (five figure income earners): Average IQ 96

Self-made millionaires (six figure income becomes seven figure wealth): Average IQ 106

Self-made decamillionaires (seven figure income becomes eight figure wealth): Average IQ 116

Self-made centimillionaires (eight figure income becomes nine figure wealth): Average IQ 126

Self-made billionares (nine figure income becomes ten figure wealth): Average IQ 136

Self-made decabillionaires (ten figure income becomes 11 figure wealth): Average IQ 146

So just the fact that Oprah is a self-made billionaire implies she has a 50% chance of having an IQ of 136 or higher.

The next question that needs to be answered is whether Oprah is likely smarter or dumber than the average self-made billionaire. One indicator is that her head is so big she has to have her hats custom made. Given that the correlation between IQ and head circumference is about 0.23, and billionaires have IQs 2.53 standard deviations above the U.S. mean of 96, we’d expect the average billionaire to have a sex adjusted head size that is 0.23(2.53 SD) = 0.58 SD bigger than normal. But Oprah’s sex adjusted head circumference is an astonishing 6.3 SD bigger than normal, which makes it 5.72 SD bigger than the average billionaire’s.

Assuming the 0.23 correlation between head size and IQ holds among self-made billionaires, Oprah would be expected to be 0.23(5.72 SD) = 1.32 SD smarter than the average self-made billionaire.

On a scale where white Americans have a mean IQ of 100 with a standard deviation of 15, and all Americans have a mean IQ of 96 with an SD of 15.8, self-made U.S. billionaires likely have a mean IQ of 136 with an SD also of 15.8. So the average self-made billionaire with a sex-adjusted head as huge as Oprah’s would have an IQ of:

1.32(15.8) + 136 = 157

But because self-made billionaires are so heterogeneous, and because the correlation between IQ and head size is so weak, you could not have much confidence at all in this estimate. All you could say with 95% confidence is that such a big headed billionaire has an IQ anywhere from 126 to 188.

Of course the typical biggest headed billionaire would be white, and so these stats don’t apply to North America’s first multi-billionaire black.

What happens when race is factored in?

For as long as IQ tests have existed, black Americans have scored about 15 points lower than white Americans. One interesting fact is that this same 15 point IQ gap exists even among high achievers. On page 374 of his book Coming Apart Charles Murray reported IQs for educated white and black Americans. Because Murray reported his IQ data using American norms, I converted to the preferred scale using white American norms:

Whites with a bachelors degree: IQ 111
Blacks with a bachelor degree: IQ 96

Whites with a masters degree: IQ 114
Blacks with a masters degree: IQ 99

Whites with a PhD or professional degree: IQ 123
Blacks with a PhD or professional degree: IQ 110

As can be seen, at each level of accomplishment, blacks score roughly 15 points lower than whites. Extrapolating this trend, the biggest headed billionaire (expected IQ of 157; 95% confidence interval 126 to 188), would have an expected IQ of 157 – 15 = 142 (95% confidence interval of 111 to 173) if she’s black.

Further, an IQ of about 140 is corroborated by Oprah’s computer scored idea density, and a historiometric estimate of her childhood IQ.

Assuming there are about 42 million African Americans, and that they have a mean IQ of 85 with a standard deviation that might be as high as 15, the normal curve predicts there are about 5,162 black Americans with IQs of 140 or higher. Given the new opportunities that emerged in the post-civil rights era, it would not be surprising if one of these 5,162 brilliant blacks rose up to become the richest African American of all time, and another, with her help, went on to become President of the United States.

Barack Obama, Oprah Winfrey

Obama giving the Medal of Freedom to Oprah in 2013, AP photo by Evan Vucci