25. William McKinley – IQ: 143.4

While UC Davis estimates that former President William McKinley had a well above-average IQ of 143.4, McKinley’s intelligence did not always benefit him when it came to his education. The 25th president dropped out of not one but two colleges, both Allegheny College in Meadville, Pennsylvania, and Mount Union College in Alliance, Ohio.

Still, McKinley went on to study law and attended the Albany Law School in New York. He was admitted to the bar in 1867. From there, McKinley rose through the ranks as a politician until he reached the highest office in the land. During his time as president, McKinley expanded America’s borders until his assassination in 1901.

24. James Polk – IQ: 143.4

The 11th U.S. President James Polk is estimated to have had an IQ of 143.4, and when considering his educational background, that number is even more astounding. At an early age, Polk’s bad health meant that he was not able to attend formal school like his peers. Instead, he was home-schooled for most of his life.

Despite those struggles, he passed the entrance exams for the University of North Carolina and became a mathematics and classics scholar. But he was not yet finished with impressing his peers. By the time he ran for president, he was the youngest successful candidate of his era. During his presidency, the U.S. gained both Texas and Oregon.

23. Grover Cleveland – IQ: 144

Not only was former President Grover Cleveland highly intelligent, but he was also the first and only president to leave office after serving only one term only to come back to serve a second term years later. Cleveland is number 23 on this list, and he was, coincidentally, both the 22nd and the 24th president of the United States.

Despite his high-brow IQ, Cleveland was known to be a man who enjoyed the simpler things in life. “I must go to dinner,” he once wrote as president to a friend, according to the White House website, “but I wish it was to eat a pickled herring, a Swiss cheese, and a chop at Louis’ instead of the French stuff I shall find.”

22. Andrew Jackson – IQ: 145

According to UC Davis, the 7th president of the United States and the first founding father of the Democratic Party had an IQ of 145, compared to the current U.S. average IQ of 98. But before he was president, Jackson earned himself a reputation during his time as a lawyer and for being a war hero during the War of 1812.

Jackson’s education has been described as “erratic.” He took time off schooling when he joined the local militia during the Revolutionary War at age 13, and began studying law as a teenager. Apparently, he was pretty good at it, considering he was appointed prosecuting attorney for his district at age 21.

21. Dwight Eisenhower – IQ: 145.1

President and Army General Dwight David “Ike” Eisenhower might not hold the highest IQ on this list, but he was still considered to be a political genius. After excelling in high school, President Eisenhower went on to excel at West Point. On D-Day in 1944, he was the Supreme Commander of the Allied troops that invaded France and ultimately helped to turn the tide of World War II in Western Europe.

Despite being incredibly smart, Eisenhower was known to try to stay away from people he deemed “scholars.” Instead, he decided to use his intelligence to help the U.S. military. Unfortunately for Eisenhower, he ended up having to spend a lot of his time with the intellectual elite he’d tried all his life to avoid, once he became the 34th president of the United States.

20. Benjamin Harrison – IQ: 145.4

Benjamin Harrison is best known as the president who served between Grover Cleveland’s first and second terms, as well as for his promotion of free trade by signing the Sherman Antitrust Act. But although Harrison may be one of the lesser-known presidents in history, he was always destined for greatness, and not just because he was a successful lawyer who began his own firm.

Intelligence and ambition ran in Harrison’s genes. His father was William Henry Harrison, aka the 9th president of the United States, and his great-grandfather was the same Benjamin Harrison who was a founding father of the United States with a signature on the Declaration of Independence.

19. Martin Van Buren – IQ: 146

It takes a good amount of intelligence to successfully negotiate in Washington DC, and Martin Van Buren was particularly gifted at sealing the deal. During his time in the Senate, Van Buren was so good at getting his legislation passed that his friends famously called him the “Little Magician,” while his enemies dubbed him “Sly Fox.”

Van Buren had planned to use those skills as governor of New York. But he quickly gave up his seat just 12 weeks into the job in order to become President Andrew Jackson’s secretary of state and, later, Jackson’s vice president. As history would have it, he would eventually move on to serve as the 8th president of the United States.

18. Rutherford Hayes – IQ: 146.3

The 19th President of the United States, Rutherford Hayes, was not born into an elite intellectual family. Instead, he was the son of an Ohio farmer. His estimated 146.3 IQ would end up boosting him to Kenyon College, where he would gradate at the top of his class in 1842.

From there, he went on to study at Harvard Law School before setting up a successful legal practice in Ohio and, lest we forget, ending up becoming president of the United States. While Hayes was committed to being a one-term president, he was able to pass laws that would have implications way beyond his term, such as allowing female lawyers to practice in front of the Supreme Court.

17. William Henry Harrison – IQ: 146.3

William Henry Harrison is known as being the first president to die while in office, and also served the shortest term of any president. Harrison died from typhoid, pneumonia, or paratyphoid fever just 31 days after swearing in as president. But on this list, Harrison is remembered for having one of the highest IQs in the Oval Office.

Harrison studied medicine in Richmond, Virginia, and in Philadelphia, up until his father’s death in 1791. After that, Harrison was confronted with just how dire his family’s financial situation was. The future leader was forced to end his studies and enlisted in the army before ultimately launching his political career.

16. Franklin Pierce – IQ: 147

When New Hampshire native Franklin Pierce was first elected to serve in the highest and most powerful position in the land, at the time he was the youngest person to have ever done so, at age 47. Having achieved a feat like that, it is no surprise that UC Davis estimated Pierce to have had an IQ of 147.

Sadly, one of the defining outcomes of Pierce’s presidency is that it was said to have set the stage for the American Civil War. As Pierce tried to extend the United States into western territories, he announced that new areas like Kansas should decide for themselves whether slavery was allowed. Ultimately, that decision exaggerated tensions between the north and the south. Pierce served for just one term.

15. John Tyler – IQ: 148.1

When President William Henry Harrison passed away just 31 days into his presidency, his running mate John Tyler also became the shortest-serving vice president of all time. That is because Tyler was quickly and unexpectedly thrust into the position of 10th President of the United States just one month into the new administration.

Along with Tyler’s high IQ, his family’s lineage meant that he was practically destined for politics. Tyler’s father was not only an old friend and college roommate of none other than one Thomas Jefferson, but he was also well-regarded in Michigan politics. The Tyler family could trace its roots in America back to 17th century colonial Williamsburg.

14. Millard Fillmore – IQ: 149

Millard Fillmore might have ran for a second presidential term under the endorsement of the Know-Nothing Party, but judging by his exceptionally high IQ of 149, we would guess that he knew far from nothing. And it was likely that high IQ that lifted Fillmore from a poverty-stricken childhood growing up with “virtually no formal schooling” to serving as President of the United States.

Fillmore started his more formal education as a law clerk for a wealthy landowner, and later went on to teach law himself. In 1849, this member of the Whig Party was elected as vice president of the United States, where he was eventually promoted to president after the death in office of former President Zachary Taylor.

13. Abraham Lincoln – IQ: 150

Abraham Lincoln was not only the tallest man to ever hold the highest office in the land, but he was also one of the smartest. Lincoln showed signs of his high IQ from very early on in life. From his youth onward, he was an avid reader, and taught himself to read despite both of his parents’ illiteracy.

Neighbors who lived near Lincoln during his childhood remembered that the young man used to travel for miles in bad weather just to pick up new books. His education was lackluster, and he once said that he learned “by littles,” meaning a little here and a little there. Ultimately, he became one of the most well-regarded presidents in U.S. history.

12. Franklin Roosevelt – IQ: 150.5

Unlike the humble beginnings of some other presidents, Franklin Delano Roosevelt grew up in the lap of luxury. He was privately educated at home until he reached age 14, and then moved on to a prep school in Massachusetts before starting his studies at Harvard University. But his stunning academic achievements did not stop there.

Roosevelt studied law at Columbia University and used his fresh law degree to work at one of the top legal firms on Wall Street. But while he excelled in school and in law, his heart was never truly in it. Instead, he turned to politics as a way to enter public service, at the urging of his wife Eleanor.

11. Chester Arthur – IQ: 152.3

Long before he got into politics, Chester Arthur was a man who used his own intelligence to help those who were less fortunate. Arthur started his education at Union College and, like many other past presidents in the U.S., went on to earn his law degree.

Long before Arthur rose to become the 21st president of the United States, he was known as a tough lawyer and fierce abolitionist. His representation of a young African American woman who was forced off of a streetcar reserved for white passengers led to New York’s law forbidding discrimination on public transportation. Ultimately, his victories in court led him to chase political victories.

10. James Garfield – IQ: 152.3

According to the study performed by UC Davis, James Garfield just made the cut for the top ten former presidents with the highest IQs. Garfield’s intellect was discovered pretty early on in his life, considering he was elected president of an Ohio college at the age of just 25 years old.

Eventually, Garfield left the world of academia behind to pursue politics. He served for nine terms in the U.S. House of Representatives before moving on up to the position of the 20th president of the United States. Unfortunately, he served the second-shortest term after he was assassinated 200 days into office.

9. Theodore Roosevelt – IQ: 153

It takes a smart person to be the youngest president of the United States at the time. After making a name for himself in the Spanish-American War, Theodore Roosevelt became the 26th president in 1901, ushering in a new, exciting time for American politics that embraced progressive reforms and strengthened the nation’s foreign policy.

Roosevelt’s parents identified their son’s high intelligence early on in his life, and he was educated by private tutors before he went on to attend Harvard. For a brief period of time, he studied law at Columbia Law School, but instead he decided to turn to writing and politics. And it is a good thing that he did, seeing as his policies still shape some of America’s laws today.

8. John Adams – IQ: 155

John Adams was the second person to ever hold the office of president of the United States, the first vice president ever, and the 8th smartest man to have served in the Oval Office. But if his father could have had it his way, John Adams would have had a markedly different career path — as a church minister!

From an early age, Deacon John Adams, the former president’s father, pushed his three sons to join the ministry. Adams seemed well on his way, as he graduated from Harvard and began teaching. But instead, Adams was drawn to law and politics. He was also drawn to his eventual wife, Abigail Adams, who was said to be just as intelligent and independent as her husband.

7. Woodrow Wilson – IQ: 155.2

Beyond leading the United States to victory in World War I, creating the League of Nations, and receiving the 1919 Nobel Peace Prize, Woodrow Wilson was, unsurprisingly, an extremely smart man. According to UC Davis, his IQ was estimated to be about 155.2.

The eventual 28th president was also known to be dyslexic since he was a child, and could not read or write until he was 10 years old. Despite his high IQ and his efforts, Wilson’s dyslexia meant that he was never a very fast reader. But this did not seem to get in the way of eventually holding the top job in the country.

6. Jimmy Carter – IQ: 156.8

Jimmy Carter came from an unusual upbringing. His father was a state legislator who also worked in a peanut warehouse, while his mother was a nurse who decided to enroll in the Peace Corps to India at age 68. Meanwhile, Carter himself attended Georgia Southwestern College and the Georgia Institute of Technology as well as the U.S. Naval Academy.

After serving in the U.S. Navy for seven years, Carter returned home and began a career in politics. While his one-term presidency from 1977 to 1981 was known for being filled with a heaping share of international conflicts, Carter eventually went on to earn himself a Nobel Peace Prize in 2002.

5. Bill Clinton – IQ: 159

The 42nd President of the United States, Bill Clinton, is said to hold the 5th highest IQ of any person to have held the presidential office. And that is not just because Clinton oversaw the United States’ longest peacetime economic expansion.

Clinton’s promising intellect was apparent early on. He studied international affairs at Georgetown University in Washington DC, just a few miles from where he would eventually hold office. At the time, he got an early introduction to politics by working as an intern for Senator J. William Fulbright, and later earned the position of Rhodes Scholar at the University of Oxford.

4. John F. Kennedy – IQ: 159.8

John F. Kennedy was the youngest person ever to be elected president, and when he was assassinated, he unfortunately became the youngest president to die in office, too. But while his death shows a dark period in American history, he was known in life to be extremely bright, with an estimated IQ of 159.8, just fractions of points below a genius-level IQ.

Long before his presidency, as a young boy, Kennedy was known to engage in “intellectual competitions” with his eight siblings. Kennedy’s parents expected his older brother Joe to go into politics. But when Joe died during World War II, the family’s political ambitions were passed onto John, who successfully carried the torch up until the day he died.

3. James Madison – IQ: 160

If a person has an IQ of 160 and above, they are considered to be a genius. The 4th U.S. President James Madison apparently met that high standard. But we would expect nothing less from one of the founding fathers of the United States and the man who is widely thought of as the Father of the Constitution.

Even before his presidency, Madison was making history. He was one of the men who helped publish the Federalist Papers. What’s more, he sponsored the first ten amendments to the Constitution, now known as the Bill of Rights, while in the House of Representatives. We’d say he’s definitely a genius.

2. Thomas Jefferson – IQ: 160

Here are some numbers that are equally as impressive as Thomas Jefferson’s genius-level IQ: he was the first author to draft the Declaration of Independence, he was the first to hold the office of secretary of state, he was the second to be vice president, and he was the third president of the United States.

Jefferson spent his life fighting for the separation of church and state, a founding principle of America. During his presidency, Jefferson was responsible for the Louisiana Purchase, doubling the size of the United States. Those who knew him said that he was eloquent. Still, he was said to be a much better writer than he was a public speaker.

1. John Quincy Adams – IQ: 175

John Quincy Adams cemented his place into U.S. history courses as being the 6th president of the United States, but he was also known to be the smartest. UC Davis found that his IQ was estimated to be an astounding 175 — well above that which is considered genius.

In his youth, Adams traveled with his father, none other than former President John Adams, to Europe where he was educated at private schools. There, Adams quickly picked up French and Dutch. And it seemed that Adams was well aware of his intelligence; he wrote in an early diary that his writings would be “next to the Holy Scriptures, the most precious and valuable book ever written by human hands.” How humble!

Sources: UC Davis, Encyclopedia Britannica, The White House