How Old is Joe Biden? President-Elect Will be America's Oldest Ever Commander in Chief

President-elect Joe Biden is celebrating his birthday today, November 20, but how old is Biden?

Joseph Robinette Biden Jr. was born on November 20, 1942, in Scranton, Pennsylvania, which means the president-elect turns 78 today.

At 78-years-old, Biden will be the oldest president to assume office, a record previously held by President Donald Trump, who was 70 on his Inauguration Day in 2017. The president-elect is four years older than Trump, who turned 74 on June 14, 2020.

Before Trump, Ronald Reagan was the oldest man to be elected president, as he was 69-years-old at the time of his inauguration in 1981.

Other than Biden, Trump, and Reagan, the oldest presidents at the time of their inauguration were William Henry Harrison, who was 68 (and died within a month of being in office), followed by James Buchanan at the age of 65. George H. W. Bush was 64 years and 222 days old when he was inaugurated, while Zachary Taylor was 64 years and 100 days old.

Joe Biden
President-elect Joe Biden speaks during a campaign kickoff rally, May 18, 2019, in Philadelphia, Pennsylvania. Biden celebrates his 78th birthday today, making him the oldest man to be elected president in U.S. history. Getty/Drew Angerer

But this isn't the only age-related record Biden will break when he becomes president in January 2021.

President-elect Biden will also become the oldest sitting president in U.S. history. Reagan held this record previously, leaving office at the age of 77, followed by Trump, who will be 74 when he leaves office.

The oldest sitting presidents other than Biden, Trump, and Reagan, were Dwight Eisenhower, who was 70 when he left office, Andrew Jackson, who was 69 years and 354 days old, and Buchanan, who was 69 years and 315 days old.

Conversely, the youngest president at the age of his inauguration was Theodore Roosevelt, who was 42. Roosevelt is followed by John F. Kennedy, who was 43, and Bill Clinton, who was 46 years and 154 days old on their inauguration days, respectively. Ulysses S. Grant was 46 years and 311 days old, while Barack Obama was 47 when he was inaugurated in 2009.

There is no maximum age at which someone can be elected president—but there is a minimum, according to the Constitution. Article II in the U.S. Constitution specifies a minimum age of 35 in its list of requirements for presidential candidates.

Article II says: "No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President; neither shall any person be eligible to that Office who shall not have attained to the Age of thirty-five Years, and been fourteen Years a Resident within the United States."