How Intelligent Was the Nation's Previous Head of States? Former U.S. Presidents IQs, Ranked


| LAST UPDATE 01/05/2022

By Ray Zhang

Being the leader of the U.S. is no easy task, but just how smart were the nation's presidents? A researcher at UC Davis used various intelligence factors to estimate the previous chief of states' IQs. Find out who ranked at number one.

42. Ulysses S. Grant - IQ: 130.0

While Ulysses S. Grant might've had the lowest IQ of 130.0, out of everyone on this list, based on a UC Davis study, that didn't stop him from having a positive impact. Before becoming the 18th president of the United States, Grant was mocked in school and sometimes called "useless," as he didn't show much interest in academics.

Ulysses Grant PresidentUlysses Grant President
Getty Images via Hulton Archive

However, he proved his classmates wrong in 1868 when he won the presidential election and began serving in 1869. Before his term, Grant led the Union Army as Commanding General of the United States Army during the civil war. He also became the first president to circumnavigate the world, meeting with countless foreign leaders.

41. George W. Bush - IQ: 138.5

George W. Bush served as the 43rd President from 2001-2009. With an IQ of 138.5 and a degree from an Ivy League, research suggests that the former commander in chief has above-average intelligence.

George Bush, Presidential FactsGeorge Bush, Presidential Facts
Chip Somodevilla / Staff via Getty Images

Bush attended Texan public schools before going to Phillips Academy in Massachusetts, where he became a head cheerleader and played baseball. The former commander then went to Yale University and Harvard Business School, before rising to the presidency.

Advertisement - Continue Reading Below

40. James Monroe - IQ: 138.6

Just because James Monroe had the second-lowest IQ, 138.6, on this list, according to studies, many Americans proudly recognized his ability to run an above-average operation during his time in the White House. Before getting elected as the fifth president, Monroe served as President George Washington's ambassador to France.

James Monroe PresidentJames Monroe President
Getty Images via Stock Montage

Alongside President Jefferson, he helped negotiate the Louisiana Purchase. Monroe's remembered for creating the Monroe Doctrine, a policy of opposing European colonialism in the U.S. Even with a lower IQ, Monroe wanted to "promote intelligence among the people as the best means of preserving our liberties."

Advertisement - Continue Reading Below

39. William Howard Taft - IQ: 139.5

With an estimated IQ of 139.5, William Howard Taft wasn't always seen as the brightest student, but his parents pushed him to keep striving towards success, and that's exactly what he did. Taft served as the 27th U.S. president starting in 1909, and he was also the country's 10th Chief Justice.

William Taft PresidentWilliam Taft President
Getty Images via Hulton Archive

This made Taft the only person to hold a position in both offices, proving that he indeed was a brilliant man. While he wasn't reelected for a second term, Taft was able to look back at his work with pride and accept that "We are all imperfect," he said. "We can not expect perfect government."

Advertisement - Continue Reading Below

38. James Buchanan - IQ: 139.6

Before becoming the 15th president of the United States, James Buchanan was a Federalist party member. However, he eventually became a Democrat, realizing that his party would come to an end. With an IQ of 139.6, according to a study by UC Davis, Buchanan was a states' rights advocate, but many Americans critiqued his work.

James Buchanan PresidentJames Buchanan President
Getty Images via Bettmann

Historians often criticize Buchanan's decision not to address slavery in the Southern states, categorizing him as one of the country's worst presidents. However, he still accomplished many things during his political career, despite having a considerably lower IQ than many other presidents.

Advertisement - Continue Reading Below

37. Zachary Taylor - IQ: 139.8

During his lifetime, Zachary Taylor certainly knew a thing or two about defending his country, as he led troops in five winning battles during the Mexican-American War. His military success helped him become elected as America's 12th president, although, apparently, that wasn't always his plan.

Zachary Taylor PresidentZachary Taylor President
Getty Images via Hulton Archive

"The idea that I should become President seems to me too visionary to require a serious answer," Taylor explained before getting elected. "It has never entered my head." But he indeed served as president, with an approximate IQ of 139.8. however, he sadly passed away from a sudden illness after just 16 months in office.

Advertisement - Continue Reading Below

36. Andrew Johnson - IQ: 139.8

This might come as a shock, but the 17th president of the U.S. never received a formal education and had an IQ of 139.8, based on some studies. However, Andrew Johnson learned the necessary skills to become a politician with his determination and served as Abraham Lincoln's vice president until Lincoln was assassinated in 1865.

Andrew Johnson PresidentAndrew Johnson President
Getty Images via Buyenlarge

Because of this tragedy, Johnson became president. But he was impeached by the House of Representatives in 1868 due to conflicts with Congress. And when this happened, he told the people, "Let them impeach and be damned." After his impeachment, Johnson was elected to the senate, something unheard of for former presidents.

Advertisement - Continue Reading Below

35. Harry S. Truman - IQ: 139.8

Harry S. Truman served as vice president to Franklin D. Roosevelt, and he became commander in chief after Roosevelt's untimely death. Truman stepped up to the job and took office from 1945 to 1953. Among other things, the former leader is known for implementing the Marshall Plan and establishing the Truman Doctrine.

Harry Truman, U.S. HistoryHarry Truman, U.S. History
PhotoQuest Contributor via Getty Images

So what did the man with a predicted IQ of 139.8 have to say about leadership? "Men make history and not the other way around," Truman once famously said. "In periods where there is no leadership, society stands still. Progress occurs when courageous, skillful leaders seize the opportunity to change things for the better."

Advertisement - Continue Reading Below

34. Warren G. Harding - IQ: 139.9

Before becoming a politician, William G. Harding ran a successful newspaper before serving in Ohio's State Senate. When he first ran for president in 1920, his odds weren't looking too favorable, but over time, he gained more votes throughout the country and became the 29th president of the United States.

Warren Harding PresidentWarren Harding President
Getty Images via Library of Congress

During his presidency, he was well-regarded by many, as he seemingly made significant improvements to the government, with an estimated IQ of 139.9. However, Harding sadly passed away in 1923 during his term. After he passed, various scandals from Harding's time in the Oval Office came to light, changing his reputation.

Advertisement - Continue Reading Below

33. George Washington - IQ: 140.0

It's probably hardly surprising that the first president of the United States is extremely smart and estimated to have an IQ of 140. Washington, known as the Founding Father of America, served the land from 1789 to 1797. But the former leader didn't let the title get to his head.

George Washington, Presidents' IQsGeorge Washington, Presidents' IQs
Gilbert Stuart / Public Domain via Wikimedia Commons

It seems that Washington was a modest man. "But lest some unlucky event should happen unfavorable to my reputation, I beg it may be remembered by every gentleman in the room that I, this day, declare with the utmost sincerity, I do not think myself equal to the command I am honored with," he once said.

Advertisement - Continue Reading Below

32. Gerald Ford - IQ: 140.4

With an IQ of 140.4, according to a UC Davis study, Gerald Ford was America's 38th president, beginning in 1974. He greatly impacted the country by signing the Helsinki Accords, which brought America closer to detente during the Cold War. Before politics, Ford was deciding between playing football and attending law school.

Gerald Ford President Gerald Ford President
Getty Images via Bob Riha, Jr.

But he decided to study law while taking a job as an assistant football coach. He was chosen as Richard Nixon's vice president, but after Nixon resigned in 1974, Ford stepped into office. When he was sworn in, he told the people, "My fellow Americans, our long national nightmare is over."

Advertisement - Continue Reading Below

31. Lyndon B. Johnson - IQ: 140.6

Supposedly, Lyndon B. Johnson declared he would someday become president at age 12, with an approximate IQ of 140.6. And he certainly made his dream into a reality in 1963, as he became America's 36th president. However, this happened under unfortunate circumstances, after John F. Kennedy was assassinated.

Lyndon Johnson PresidentLyndon Johnson President
Getty Images via Bettmann

While some people criticized LBJ for how he handled the Vietnam War, many historians credit him for passing significant laws to improve civil rights, the environment, and other matters during his presidency. He often exclaimed, "Books and ideas are the most effective weapons against intolerance and ignorance."

Advertisement - Continue Reading Below

30. Calvin Coolidge - IQ: 141.6

Calvin Coolidge, who served as America's 30th president, was a man of few words. He once wrote, "The words of a president have an enormous weight and ought not to be used indiscriminately." With an estimated IQ of 141.6, Coolidge started his political career in Massachusetts, eventually becoming governor.

Calvin Coolidge PresidentCalvin Coolidge President
Getty Images via Bettmann

Some of his work in Boston brought him into the spotlight, and he became vice president during Warren G. Harding's presidency. Unfortunately, Harding passed away suddenly in 1923, putting Coolidge as the country's leader, and he was said to have restored public confidence in the White House by many.

Advertisement - Continue Reading Below

29. Herbert Hoover - IQ: 141.6

As a child, this historical figure with a predicted IQ of 141.6 wasn't too keen on schooling. Hoover did little reading aside from the Bible and dropped out of school at the age of 13. But years later, the former chief of state attended Stanford University, despite a lack of a high school diploma and failing all of the entrance exams except one.

Herbert Hoover, Smartest PresidentsHerbert Hoover, Smartest Presidents
Topical Press Agency / Stringer via Getty Images

Hoover took office from 1929 to 1933 and expressed his gratefulness for the opportunities provided to him in the United States. "My country owes me nothing," he said. "It gave me, as it gives every boy and girl, a chance. It gave me schooling, independence of action, opportunity for service and honor."

Advertisement - Continue Reading Below

28. Ronald Reagan - IQ: 141.9

According to the research conducted by the University of California at David, former head of state Reagan had an intelligence quotient of 141.9. Ronald was president from 1981 to 1989. The iconic leader attended Dixon High School and later Eureka College, where he was a member of the football and swim teams.

Ronald Reagan, U.S. PresidentsRonald Reagan, U.S. Presidents
Wally McNamee / Contributor via Getty Images

After college and before becoming president, Nixon was actually in show business. The Hollywood actor turned U.S. president was smart and funny. "I have left orders to be awakened at any time in case of national emergency - even if I'm in a Cabinet meeting," he once famously joked.

Advertisement - Continue Reading Below

27. Richard Nixon - IQ: 142.9

Richard Nixon's journey to the Oval Office wasn't a simple one. With an estimated IQ of 142.9, the famous leader excelled in school growing up and was an all-star debater. After graduation, Nixon was offered a tuition grant to attend Harvard University.

Richard Nixon, American PresidentsRichard Nixon, American Presidents
Bettmann / Contributor via Getty Images

But his brother's illness led the 37th president to stay in his hometown and take care of the family business. Years later, Nixon received a full scholarship for Duke University School of Law and, well, the rest is history. As Richard once said, "The American dream does not come to those who fall asleep."

Advertisement - Continue Reading Below

26. George H. W. Bush - IQ: 143.0

They say the apple doesn't fall far from the tree, and perhaps George W. Bush inherited his high IQ from his father. UC Davis's research estimates the 41st president had an IQ of 143. Before occupying the highest office in the land, Bush attended Yale College.

George Bush, American PresidentsGeorge Bush, American Presidents
Consolidated News Pictures / Contributor via Getty Images

Following his completion of formal education, Bush went on to become a member of the U.S. House of Representatives, a UN Ambassador, and later vice president. The leader's secret to success? Furry friends. "Let me give you a little serious political advice. One single word: puppies. Worth the points," the late president joked.

Advertisement - Continue Reading Below

25. William McKinley - IQ: 143.4

The 25th president is predicted to have had an IQ of 143.4. But looking at his story, one could argue that there's no set road to success. Before becoming chief of state, McKinley dropped out of two higher education institutions: Allegheny College in Pennsylvania and Mount Union College in Ohio.

William McKinley, American HistoryWilliam McKinley, American History
Library of Congress Contributor via Getty Images

The former leader eventually graduated from the Albany Law School in New York, and what followed was a successful political career. "That's all a man can hope for during his lifetime - to set an example - and when he is dead, to be an inspiration for history," McKinley once said.

Advertisement - Continue Reading Below

24. James Polk - IQ: 143.4

The University of California, Davis predicts that this former leader had a high IQ of 143.4. This might make his educational history somewhat surprising. Polk didn't attend a formal school to due poor health and spent most of his life being home-schooled.

James Polk, Interesting HistoryJames Polk, Interesting History
George Peter Alexander Healy / Public domain via Wikimedia Commons

But the homeschooling proved effective, and the eleventh president was able to pass his entrance exams for the University of North Carolina. There, he studied mathematics. When Polk became president in 1854, he was the youngest U.S. leader so far. Talk about making history!

Advertisement - Continue Reading Below

23. Grover Cleveland - IQ: 144

Gover Cleveland holds the title of both the 22nd and 24th president of the United States. The previous head of state boasted an IQ of 144 and is the only leader in American history to serve two non-consecutive terms in the Executive Branch. Cleveland took office from 1885 to1889 and again from 1893 to 1897.

Grover Cleveland, Presidential FactsGrover Cleveland, Presidential Facts
Library of Congress / Contributor via Getty Images

But for this highly intelligent and experienced man, there was always more to be learned. "I know that I am honest and sincere in my desire to do well," Cleveland is quoted as saying. "But the question is whether I know enough to accomplish what I desire."

Advertisement - Continue Reading Below

22. Andrew Jackson - IQ: 145

Andrew Jackson was the first founding father of the Democratic Party, and UC Davis estimates the leader had an impressive IQ of 145. Before becoming America's seventh president in 1829, the former head of state rose to fame after serving as general in the U.S. army.

Andrew Jackson, U.S. HistoryAndrew Jackson, U.S. History
Ralph Eleaser Whiteside Earl / Public domain via Wikimedia Commons

One of the historical leaders' values? Admitting when you're wrong. "Any man worth his salt will stick up for what he believes is right, but it takes a slightly better man to acknowledge instantly and without reservation that he is in error," he once said.

Advertisement - Continue Reading Below

21. Dwight Eisenhower - IQ: 145.1

The 34th president is predicted to have had an IQ of 145.1. Eisenhower served in the Oval Office from 1953 to 1961. Before that, he led an impressive military career during World War II and became a five-star general. The former leader's key to success? Giving your absolute best.

Dwight Eisenhower, Presidents' IQsDwight Eisenhower, Presidents' IQs
Fox Photos / Stringer via Getty Images

"I believe when you are in any contest you should work like there is always to the very last minute a chance to lose it," Eisenhower said. "This is battle, this is politics, this is anything. So I just see no excuse if you believe anything enough for not putting your whole heart into it. It is what I do."

Advertisement - Continue Reading Below

20. Benjamin Harrison - IQ: 145.4

It seems that leadership (and intellectual capacity) were in Benjamin Harrison's genes The 23rd president was the grandson of William Henry Harrison, the nation's ninth president, and a great-grandson of founding father Benjamin Harrison. Before becoming chief of state, he was a lawyer with his own firm.

Benjamin Harrison, Smartest PresidentsBenjamin Harrison, Smartest Presidents
Eastman Johnson / Public domain via Wikimedia Commons

Harrison served in between Grover Cleveland's two non-consecutive terms. "I knew that my staying up would not change the election result if I were defeated, while if elected I had a hard day ahead of me. So I thought a night's rest was best in any event," he is famously quoted as saying after the elections.

Advertisement - Continue Reading Below

19. Martin Van Buren - IQ: 146

With a whopping estimated IQ of 146, Martin Van Buren is ranked number 19 on this list. Buren had an impressive career: he was a founder of the Democratic Party, served as the ninth governor of New York, and was Andrew Jackson's secretary of state and later his vice president.

Martin Buren, U.S. PresidentsMartin Buren, U.S. Presidents
Daniel Hass via Wikimedia Commons

But even for a smart person like Van Buren, holding the highest office in the land is likely an extremely challenging task. "As to the presidency, the two happiest days of my life were those of my entrance upon the office and my surrender of it," he once said.

Advertisement - Continue Reading Below

18. Rutherford Hayes - IQ: 146.3

The son of an Ohio farmer, Hayes graduated at the top of his class and went on to Kenyon College. The star student then earned a spot in Harvard Law School and started his own firm in Ohio before becoming the 19th President of the U.S. UC Davis estimates he had an IQ of 146.3.

Rutherford Hayes, American PresidentsRutherford Hayes, American Presidents
Bettmann / Contributor via Getty Images

For Hayes, walking the walk was as important as talking the talk. "Personally I do not resort to force - not even the force of law - to advance moral reforms," he said. "I prefer education, argument, persuasion, and above all the influence of example."

Advertisement - Continue Reading Below

17. William Henry Harrison - IQ: 146.3

William Henry Harrison went down in the history books as the first head of state to die while in office. The former commander in chief sadly passed away from typhoid, pneumonia, or paratyphoid just 31 days into his first term and became the shortest-serving U.S. president.

William Harrison, American PresidentsWilliam Harrison, American Presidents
Hulton Archive Stringer via Getty Images

Harrison is predicted to have had an IQ of 146.3, so it's probably not a shocker that as a young man he studied medicine in Virginia and Philadelphia. Financial struggles ultimately led him to quit his studies and enlist in the army. William then became a major general during the War of 1812.

Advertisement - Continue Reading Below

16. Franklin Pierce - IQ: 147

Former President Pierce was 47 when he became the U.S.'s top leader. At the time, Franklin was the youngest person to have occupied the position. Perhaps his high IQ of 147, as estimated by UC Davis, helped him achieve such great success at a young age.

Franklin Pierce, American HistoryFranklin Pierce, American History
Bettmann / Contributor via Getty Images

The wise Pierce looked to the leaders who came before him for guidance. "The founders of the Republic dealt with things as they were presented to them, in a spirit of self-sacrificing Patriotism and as time has proved, with a comprehensive wisdom which it will always be safe for us to consult," he said.

Advertisement - Continue Reading Below

15. John Tyler - IQ: 148.1

John Tyler became the tenth President of the U.S. after a series of unfortunate events. When President William Henry Harrison died 31 days into his term, Tyler unexpectedly became head of state. The former leader is estimated to have boasted an IQ of 148.1, but popular opinion was not in his favor while in office.

John Tyler, Interesting HistoryJohn Tyler, Interesting History
UniversalImagesGroup / Contributor via Getty Images

"My own personal popularity can have no influence over me when the dictates of my best judgment and the obligations of an oath require of me a particular course," The former president said at the time. "Under such circumstances, whether I sink or swim on the tide of popular favor is, to me, a matter of inferior consideration."

Advertisement - Continue Reading Below

14. Millard Fillmore - IQ: 149

Former President Fillmore grew up in poverty, the son of tenant farmers in New York. Perhaps his high intelligence quotient of 149 is what helped him become a successful attorney despite having little formal education. The natural-born leader was a member of the U.S. House of Representatives before becoming vice president in 1848.

Millard Fillmore, Presidential FactsMillard Fillmore, Presidential Facts
White House / Public domain via Wikimedia Commons

He then succeeded to the nation's highest office when President Zachary Taylor passed away in 1850. "The man who can look upon a crisis without being willing to offer himself upon the altar of his country is not for public trust," the former commander in chief once famously said.

Advertisement - Continue Reading Below

13. Abraham Lincoln - IQ: 150

Abraham Lincoln is arguably one of the most famous leaders in U.S. history. He took office in 1861 as the 16th president and went down in history for leading the nation through the American Civil War. Lincoln preserved the Union and abolished slavery before his untimely assassination in 1865.

Abraham Lincoln, U.S. HistoryAbraham Lincoln, U.S. History
Anthony Berger / Public domain via Wikimedia Commons

Before his passing, the legendary head of state wanted people to know that anyone was capable of rising to the presidency. "I happen temporarily to occupy this big White House. I am living witness that any one of your children may look to come here as my father's child has," he said.

Advertisement - Continue Reading Below

12. Franklin Roosevelt - IQ: 150.5

Franklin Roosevelt's educational track record might make his high IQ less surprising. The 32nd president was homeschooled by private tutors until he was 14 years old and then went to a boarding school in Massachusetts. Roosevelt later attended Harvard College and Columbia Law School.

Franklin Roosevelt, Presidents' IQsFranklin Roosevelt, Presidents' IQs
UniversalImagesGroup / Contributor via Getty Images

One of the most important lessons the former chief of state learned throughout his life? Don't be afraid to try. "It is common sense to take a method and try it. If it fails, admit it frankly and try another. But above all, try something," Roosevelt said.

Advertisement - Continue Reading Below

11. Chester Arthur - IQ: 152.3

UC Davis estimates America's 21st president had an IQ of 152.3. Before taking his seat in the White House, Chester Arthur was an abolitionist and lawyer. He represented Elizabeth Graham after she was denied a seat on a streetcar because of her race. The dedicated attorney won the case, which led to NYC's streetcars becoming desegregated.

Chester Arthur, Smartest PresidentsChester Arthur, Smartest Presidents
Hulton Archive / Stringer via Getty Images

Arthur's secret to good leadership? "Be fit for more than the thing you are now doing," he said. "Let everyone know that you have a reserve in yourself; that you have more power than you are now using. If you are not too large for the place you occupy, you are too small for it."

Advertisement - Continue Reading Below

10. James Garfield - IQ: 152.3

James Garfield entered office in 1881 and makes it onto this list's top 10 with a predicted IQ of 152.3. The 20th president was born into poverty and education was his key out. Garfield studied law and became an attorney, rising in leadership until becoming head of state. Sadly, he was assassinated just over six months later.

James Garfield, U.S. PresidentsJames Garfield, U.S. Presidents
Epics / Contributor via Getty Images

"There are men and women who make the world better just by being the kind of people they are. They have the gift of kindness or courage or loyalty or integrity," Garfield said. "It really matters very little whether they are behind the wheel of a truck or running a business or bringing up a family. They teach the truth by living it."

Advertisement - Continue Reading Below

9. Theodore Roosevelt - IQ: 153

Before he became one of the four famous leaders depicted on Mount Rushmore, a young Roosevelt was homeschooled by tutors and his parents. The man with a predicted IQ of 153 then attended Harvard, where he excelled in science and philosophy. Roosevelt is arguably remembered most for his progressive policies as 26th president.

Theodore Roosevelt, American PresidentsTheodore Roosevelt, American Presidents
Hulton Archive / Stringer via Getty Images

"Nothing in the world is worth having or worth doing unless it means effort, pain, difficulty," Theodore believed. "I have never in my life envied a human being who led an easy life. I have envied a great many people who led difficult lives and led them well."

Advertisement - Continue Reading Below

8. John Adams - IQ: 155

With an IQ of 155, Adams is number 8 on this list. Yet the wise leader felt that the more he learned, the less he actually knew. "The longer I live, the more I read, the more patiently I think, and the more anxiously I inquire, the less I seem to know," he said.

John Adams, American PresidentsJohn Adams, American Presidents
Hulton Archive / Stringer via Getty Images

During the American Revolution, Adams was one of the main leaders in America's fight for independence from Great Britain. The intelligent man was the country's first vice president and the second person to become president of the United States of America.

Advertisement - Continue Reading Below

7. Woodrow Wilson - IQ: 155.2

During his time as the 28th president, Wilson led the U.S. to victory in World War I and established an activist foreign policy known as Wilsonianism. The University of California at Davis estimates that the former leader had an IQ of 155.2, earning him a spot as number seven.

Woodrow Wilson, American HistoryWoodrow Wilson, American History
Topical Press Agency / Stringer via Getty Images

"You are not here merely to make a living. You are here in order to enable the world to live more amply, with greater vision, with a finer spirit of hope and achievement. You are here to enrich the world, and you impoverish yourself if you forget the errand."

Advertisement - Continue Reading Below

6. Jimmy Carter - IQ: 156.8

Former President Jimmy Carter is said to have an IQ of 156.8. Before he was commander in chief, Carter was a Georgia State Senator from 1963 to 1967 and the state's governor from 1971 to 1975. In 2002, the famous leader was awarded the Nobel Peace Prize for co-founding the Carter Center.

Jimmy Carter, Interesting HistoryJimmy Carter, Interesting History
Bettmann / Contributor via Getty Images

That's not the only positive side of his post-White House life. Discussing the perks of being an ex-president, Jimmy humorously said, "My esteem in this country has gone up substantially. It is very nice now that when people wave at me, they use all their fingers."

Advertisement - Continue Reading Below

5. Bill Clinton - IQ: 159

Before entering the White House as America's 42nd President, Clinton went to school not too far away at Georgetown University in Washington, DC. He continued his education at Oxford and then Yale Law School, where he met his future wife Hillary Rodham.

Bill Clinton, Presidential FactsBill Clinton, Presidential Facts
JOYCE NALTCHAYAN / Staff via Getty Images

UC Davis puts Clinton's IQ at 159. As for the former president's motto? Never give up. "If you live long enough, you'll make mistakes. But if you learn from them, you'll be a better person," Bill said. "It's how you handle adversity, not how it affects you. The main thing is never quit, never quit, never quit."

Advertisement - Continue Reading Below

4. John F. Kennedy - IQ: 159.8

November 1963 marked a tragic time in American history: President John F. Kennedy was assassinated. The beloved leader was the youngest president to die in office but is remembered for his charisma and brightness, as well. UC Davis's data estimates that Kennedy was the nation's fourth smartest leader, with an IQ of 159.8.

John Kennedy, U.S. HistoryJohn Kennedy, U.S. History
Historical / Contributor via Getty Images

"Life is never easy. There is work to be done and obligations to be met - obligations to truth, to justice, and to liberty," Kennedy famously said. Before taking a seat in the Oval Office, the iconic leader served in the U.S. House of Representatives and the U.S. Senate.

Advertisement - Continue Reading Below

3. James Madison - IQ: 160

James Madison is known for a variety of accomplishments: he helped publish the Federalist Papers, was the "Father of the Constitution," drafted the Bill of Rights, and was the fourth U.S. president. With an estimated IQ of 160, it's no surprise that Madison believed that knowledge equals power.

James Madison, Presidents' IQsJames Madison, Presidents' IQs
Universal History Archive / Contributor via Getty Images

"Knowledge will forever govern ignorance, and a people who mean to be their own governors must arm themselves with the power knowledge gives. A popular government without popular information or the means of acquiring it, is but a prologue to a farce or a tragedy or perhaps both."

Advertisement - Continue Reading Below

2. Thomas Jefferson - IQ: 160

The number two spot on this list goes to Thomas Jefferson, who UC Davis research approximates had an IQ of 160. He was the principal author of the Declaration of Independence and served as vice president before becoming the third president of the U.S. in 1801.

Thomas Jefferson, Smartest PresidentsThomas Jefferson, Smartest Presidents
Mather Brown / Public domain via Wikimedia Commons

Yet before Jefferson took office, he is said to have told his friend Alexander Donald, "I had rather be shut up in a very modest cottage with my books, my family and a few old friends, dining on simple bacon, and letting the world roll on as it liked than to occupy the most splendid post, which any human power can give."

Advertisement - Continue Reading Below

1. John Quincy Adams - IQ: 175

President John Quincy Adams might go down in history as the smartest U.S. president. Research indicates that the former leader may have had an IQ of 175, putting him at genius-level intelligence. Adams was a diplomat, lawyer, and the sixth U.S. president.

John Adams, U.S. PresidentsJohn Adams, U.S. Presidents
The Metropolitan Museum of Art via Wikimedia Commons

Not surprisingly, the former chief of state considered education to be the best thing one could acquire in life."To furnish the means of acquiring knowledge is ... the greatest benefit that can be conferred upon mankind," Adams said. "It prolongs life itself and enlarges the sphere of existence."

Advertisement - Continue Reading Below