The 4 most (and 5 least) intelligent US presidents based on their IQs

There are no actual IQ records for most American presidents, but psychological studies have provided some pretty good estimates of what they might be, so let’s find out which ones are the most and least intelligent.

A very early start

The most intelligent American president? It’s apparently John Quincy Adams. He had an estimated IQ of 175. But it’s not a surprise to anyone who knows a little about his life. He’d already traveled through Europe and kept detailed journals when he was 14.

He also worked as a diplomatic secretary. That’s not all. He also spoke multiple languages fluently before he finished high school. No wonder he’s at the top of this list.

A desk full of plans

In second place, we have Thomas Jefferson with an estimated IQ of 160. Jefferson collected disciplines the way some people collect comic books. He studied law, architecture, farming, languages, and political writing.

In fact, Jefferson used those skills to help him design parts of his home, Monticello. He did it while writing thousands of letters over his lifetime. Talk about smart. You can still read some of them today. 

A long route out

Bill Clinton’s only one point behind. His IQ is estimated to be 159, and his résumé is pretty good on top of that. Clinton studied at Georgetown and got a Rhodes Scholarship. He studied at Yale Law School before entering politics.

The truth is, he was already teaching law and had a reputation for having a good memory before becoming president. He was one of the smartest ones we’ve ever had.

A reactor job before politics

Sure, you might know Jimmy Carter as the peanut farmer. He didn’t have peanuts for brains, though. His IQ was estimated to be 156.8, ranking him as the fifth-smartest president in US history. It makes sense, really.

He studied at the United States Naval Academy and worked in the Navy’s nuclear submarine program. That was all before he entered politics. You’ve got to be smart to get involved with nuclear engineering and reactor systems.

A quiet climb

On the opposite side of the list, we have Calvin Coolidge. His IQ was estimated to be 127. Don’t get it wrong, that’s still above the average American IQ of 98 to 100. But he’s lower on the list than other American presidents.

Coolidge graduated from Amherst College and studied law. His climb to the top was a little slower, and his approach was different, too. It was a lot more careful and a lot less dramatic than some of the other faces on this list.

A robe after the Oval Office

Honestly, it’s kind of surprising that William Howard Taft’s on the lower end of the list. He had an IQ of 126. But that didn’t stop him from doing something that no other president has, and that’s becoming Chief Justice of the Supreme Court.

That came after he left office. He didn’t do the usual former presidential thing of writing memoirs or disappearing into speeches. No, he switched uniforms and kept on climbing. That’s a pretty smart move.

A tailor’s counter

Andrew Johnson didn’t go to school in the traditional sense. Maybe that’s why he’s lower down on the list. He was apprenticed to a tailor when he was a boy in North Carolina. It was only later that his wife, Eliza McCardle Johnson, helped him learn some important skills, like reading and writing.

She also taught him arithmetic. His IQ was estimated to be around 125. That’s definitely not something to laugh at. He still managed to become president of the United States, after all.

A small-town pressroom

There were no Ivy League lecture halls or military academies for Warren G. Harding. His IQ was apparently around 124. During his twenties, Harding scraped together some money with partners to buy the Marion Star Newspaper.

But it wasn’t some kind of giant media empire. It was your standard local paper for small-town readers, featuring local gossip and community politics. Harding spent years building the paper. Then, eventually, he became a national politician. 

A name that stuck

Ulysses S. Grant sits at the very bottom of the list. He had an estimated IQ of 120. That sort of tracks since his early life was never really academically focused, anyway. In fact, at West Point, his classmates noticed he had an odd skill.

He was able to ride horses like nobody else. Maybe that made up for his IQ. His name wasn’t even Ulysses S. Grant, but actually Hiram Ulysses Grant. The clerks at West Point made a mistake, and the new name stuck with him.

Sources: Please see here for a complete listing of all sources that were consulted in the preparation of this article.