What Is Bill Gates' IQ?

IQ often quoted online160

Published IQ test resultNone

Best-known test scoreSAT 1590 / 1600

Verdict on "160"Unverified

In short: Bill Gates' IQ is not known. The figure of 160 is a conversion from his SAT score, not the result of an IQ test, and a near-perfect SAT can't tell you how far above the top of the test someone really is. His strongest evidence is a published maths paper, not a number.

Where the Bill Gates IQ figure of 160 comes from

Ask what Bill Gates' IQ is and most websites answer 160. Some widen it to "151 to 160" or "160 to 170", and a few give oddly precise versions such as "157". We could not find any version that names an IQ test, a date or a psychologist. Gates has not published a score, and none is reported in his 2025 memoir Source Code: My Beginnings.

Unlike many celebrity IQ figures, this one does have a method behind it. Where a source is given, it is his SAT result: the 160 is what you get by running a near-perfect college admissions score through an SAT-to-IQ conversion. That makes it an estimate, not a measurement, and as the next sections show, it is an estimate built on the weakest part of the scale. It is the same pattern we found for Elon Musk's IQ, where the popular number also traces back to an SAT score.

In the terms used in our guide to the IQ of famous people, Gates' 160 sits between an estimate and a myth: there is a real test behind it, but not an IQ test, and the step from one to the other is where the certainty disappears.

Bill Gates' SAT score: 1590 out of 1600

The score that everything rests on is well documented. Gates scored 1590 out of a possible 1600 on the SAT, which he took at Lakeside School in Seattle before entering Harvard in the autumn of 1973. Biography.com notes that for years he would mention the result when introducing himself to new people, a detail that fits his own description of himself as a competitive teenager. For what an SAT score can and can't say about IQ in general, see our SAT to IQ conversion chart.

Two details are often lost when the number is repeated:

• It was not a perfect score. Many sites say Gates "aced" the SAT. He was 10 points short.
• It was on the old scale. Before the College Board re-centred the SAT in 1995, average scores were well below 500 per section, and totals near 1600 were far rarer than they are today. Our Elon Musk article explains the 1995 change in more detail.

So 1590 in the early 1970s was an exceptional result, almost certainly in the top fraction of one per cent of test takers. What it can't do is tell you how exceptional.

The ceiling problem: why a top SAT score can't give an IQ

Every test has a highest possible score. When someone scores at or just below it, you learn that their ability is at least that high, but not how far beyond it they might go. Psychologists call this a ceiling effect, and it is the main reason Gates' 160 is shakier than it looks.

A conversion has to guess where in that hidden area to place him, and the guess is what produces 160. Choose slightly different assumptions and you get 150 or 170, which is exactly the spread we see online. There are two further problems:

A 2004 study by Frey and Detterman found that SAT scores correlate strongly with general intelligence, at about 0.82, but even a correlation that high leaves a margin of more than 15 IQ points either way for any one person. You can see that margin for yourself with the correlation tool on our Elon Musk IQ page. At the very top of the scale, where Gates was, the margin only grows.

Gates at Lakeside: a computer terminal at 13

William Henry Gates III was born in Seattle on 28 October 1955. As a boy he read constantly and argued with his parents just as constantly. In Source Code he describes how the conflict at home grew bad enough that his parents took him to a therapist, Dr Charles Cressey, whom he saw for about two years. Cressey's view, as Gates retells it, was that the boy would eventually win the power struggle, and that his parents should give him room. Soon afterwards they moved him to Lakeside, a private school in north Seattle.

In 1968, when Gates was in eighth grade, the Lakeside Mothers' Club used money from its rummage sale to buy a Teletype Model 33 terminal and a block of time on a General Electric computer. Gates was 12 or 13 and was hooked at once. One of his first programs, written in BASIC, let people play tic-tac-toe against the computer. With older students including Paul Allen, he went on to swap programming work for free computer time, and the two later set up Traf-O-Data, a small business that turned traffic-counter tapes into reports for road engineers.

His school record was strong but not flawless. A reviewer of the memoir noted that the book's own fact-checking found Gates' memory of straight A's in ninth grade was wrong: he had a mix of A's and B's. It is a useful reminder that even first-hand accounts of a famous person's early brilliance tend to improve with time.

Harvard and Math 55: meeting people who were better

At Harvard, Gates enrolled in Math 55, the university's notoriously difficult introductory maths course for students with exceptional preparation. It was there that he met his limits. A freshman upstairs in his dormitory, Andy Braiterman, was better at maths than he was, and the two worked through problem sets together late into the night. Gates later named Braiterman and Jim Sethna, who became a physics professor at Cornell, as the maths stars of his year. In an interview for Walter Isaacson's history of the digital revolution, he put it plainly:

This is one of the most telling details in the whole story. Gates, the student with the 1590, found himself in a room where he was not the strongest mathematician, and he drew the practical conclusion. He moved towards applied mathematics and computing, and spent much of his time in Harvard's Aiken computer lab and playing poker, before leaving in 1975.

The pancake problem: Gates' only research paper

The strongest evidence of Gates' mathematical ability isn't a test score at all. In a class taught by the computer scientist Harry Lewis, students were set a puzzle known as the pancake problem: if you have a stack of pancakes of different sizes and a spatula that can flip any number from the top, what is the largest number of flips you could ever need to sort the stack, smallest on top?

Gates came back to Lewis with a better method than anyone had found. Working with Christos Papadimitriou, then a young assistant professor, he turned it into a paper, "Bounds for Sorting by Prefix Reversal", published in the journal Discrete Mathematics in 1979. It proved that any stack of n pancakes can always be sorted in at most (5n + 5)/3 flips, about five flips for every three pancakes. By the time it was accepted, Gates was running Microsoft in Albuquerque. Papadimitriou later recalled thinking, when Gates showed little interest in the news: "Such a brilliant kid. What a waste."

Try the problem yourself. Tap a pancake to slide the spatula under it and flip it together with everything above it.

For a small stack, a simple strategy works: flip the largest pancake to the top, then flip it to the bottom, and repeat. That needs up to two flips per pancake. Gates and Papadimitriou showed that a cleverer method never needs more than about five for every three, and also that some stacks need more than one flip per pancake however cleverly you work. Their upper bound stayed the best known for close to 30 years, until a team at the University of Texas at Dallas improved it to 18n/11, announced in 2008 and published in 2009. The exact answer for large stacks is still unknown.

A single research paper is not an IQ score either. But it is a better kind of evidence: an original solution to an open problem, checked by referees, that experts failed to beat for decades. Harry Lewis told NPR in 2008: "If he'd wanted to, he could've been a mathematician."

Bill Gates' record in brief

1. 1955
   Born in Seattle28 October, the second of three children.
2. 1968
   First programs at LakesideWrites software on the school's new computer terminal.
3. 1973
   Enters HarvardAfter scoring 1590 on the SAT. Takes Math 55.
4. 1975
   Founds MicrosoftWith Paul Allen in Albuquerque, after writing a version of BASIC for the Altair 8800. Leaves Harvard.
5. 1979
   Pancake paper publishedWith Christos Papadimitriou in Discrete Mathematics.
6. 1981
   MS-DOS ships with the IBM PCThe deal that made Microsoft the standard for personal computers.
7. 1995
   World's richest personTops the Forbes ranking for the first time, and stays there in most years until 2017.
8. 2000
   Gates FoundationSteps down as Microsoft's chief executive; the foundation becomes his main work.
9. 2007
   Harvard degree, at lastAn honorary doctorate, 32 years after he left.
10. 2025
    Source CodePublishes a memoir of his early life, the first of three planned volumes.

A record like this shows several abilities working together: technical skill, the business judgement to license MS-DOS rather than sell it, and the persistence to run a company for 25 years. IQ tests measure only the first of these well. Our guide What is IQ? explains what the tests do and don't cover.

How Gates learns: Think Weeks and 50 books a year

Gates is often described as having an extraordinary memory and reading speed. What is documented is less about speed and more about habit. He has said he reads about 50 books a year, and he has reviewed many of them on his blog, Gates Notes, for more than a decade.

At Microsoft he also became known for his "Think Weeks". Twice a year he would spend a week alone in a cabin in the Pacific Northwest, reading papers written by employees about new ideas for the company, sometimes for 18 hours a day. His 1995 memo "The Internet Tidal Wave", which turned Microsoft towards the web, came out of one of them. The habit is a reminder that what looks like raw intelligence from outside often includes a great deal of deliberate, structured effort.

In Source Code, Gates also wrote that if he were growing up today, he would probably be diagnosed on the autism spectrum, pointing to his intense focus and his difficulty reading social cues as a child. That is not the same as a statement about IQ. Neurodivergence describes how a brain processes information and interacts with the world, and it occurs at every level of measured intelligence.

Myths about Bill Gates' intelligence

If Gates scored 160, how rare would that be?

Suppose the popular number were correct. On the standard scale, where the average is 100 and the standard deviation is 15, 160 lies four standard deviations above the average. That level is reached by roughly one in every 31,600 people, which across today's world population means about 260,000 people: a group the size of a small city, spread across every country.

It is also right at the edge of what professional IQ tests can measure, which brings us back to the ceiling problem. Even if Gates sat a modern IQ test tomorrow, a result of 160 would mean "at or near the top of this test" rather than an exact position. To see how this level compares with everything below it, explore the IQ scale and score ranges, or read about the highest IQ in the world to see why claims far above 160 can't be true.

Frequently asked questions

Sources

• Gates, W. H. and Papadimitriou, C. H. (1979). Bounds for sorting by prefix reversal. Discrete Mathematics, 27(1), 47–57.
• Chitturi, B. et al. (2009). An (18/11)n upper bound for sorting by prefix reversals. Theoretical Computer Science, 410(36), 3372–3390.
• Harry Lewis recalls Bill Gates and the pancake problem, Harvard John A. Paulson School of Engineering and Applied Sciences (2008).
• Dawn of a revolution, Harvard Gazette (2013), adapted from Walter Isaacson's The Innovators: Math 55, Andy Braiterman and the quote on changing his mind about maths.
• People of ACM: Christos Papadimitriou, Association for Computing Machinery (2013): his recollection of Gates and the pancake paper.
• Even Bill Gates thinks AI is a little scary, Harvard Gazette (2025): Math 55 and his friends Andy Braiterman and Jim Sethna.
• Gates, B. (2025). Source Code: My Beginnings. Knopf: his childhood, therapy with Dr Charles Cressey and Lakeside.
• Bill Gates, Biography.com: the 1590 SAT score, Lakeside and his first program.
• Bill Gates on the autism spectrum and his childhood, Fortune (2025), on Source Code: My Beginnings.
• Review of Source Code, GeekWire (2025): therapy, Lakeside and the corrected ninth-grade grades.
• Bill Gates took solo Think Weeks in a cabin in the woods, CNBC (2019).
• Choose a lazy person to do a hard job, Quote Investigator (2014).
• Frey, M. C. and Detterman, D. K. (2004). Scholastic Assessment or g? Psychological Science, 15(6), 373–378.