Oldest US president: how old is Joe Biden, Donald Trump, who is the oldest American president in office - ages

President Joe Biden has officially announced that he will seek reelection in 2024, pleading with voters to give him another chance to "finish the job" he began when he first took office.

Biden is hoping that his first-term legislative accomplishments and more than 50 years of experience in Washington, D.C. will help him overcome any concerns about his advanced age. Though Biden is the US’ current president, and entitled to defend his seat for another term, he is the oldest leader in American history.

By November 2024, Biden will be 81, and with a potential second term presumably taking him to the ripe age of 86, his health will be a major source of debate. Many Democratic voters have stated that they would prefer that he not run, in part because of his advanced age. Biden has referred to these worries as "totally legitimate.”

Right now, Biden's biggest potential rival is once again Donald Trump, the previous US President - and the second oldest in history. In November 2022, Trump declared that he would make a third effort to obtain the keys to the White House.

But who are the oldest and youngest US presidents in the country’s relatively short existence? Here is everything you need to know.

Who are the youngest and oldest US presidents?

The median age of new US presidents at inauguration is 55 years.

Theodore Roosevelt, who took over the presidency at the age of 42 after William McKinley was assassinated, was the youngest person to do so. Roosevelt was also the youngest person to become a former president at the age of 50,

The youngest person to become president by election was John F. Kennedy, who was inaugurated at the age of 43. Kennedy, assassinated at the age of 46, was the youngest president at the end of his tenure, and his life span was the shortest of any president.

Ronald Reagan was the oldest president at the end of his tenure, at 77; this dubious honour will eventually fall to Joe Biden, who was older when he took office than Reagan was when he left.

It’s well known that Biden is the oldest US president in history. But if Trump wins the presidency (a prospect which, as it stands, looks fairly unlikely) he will be 78 years old when he is inaugurated. While this is the same age as Biden when he took office, Trump would be the second-oldest president in US history.

Trump is in fact already the second-oldest president in US history, having been sworn in for his first term as leader at the age of 70. That means that potentially, were it to come down to Biden and Trump in 2024, the race could be between the oldest and second oldest US presidents in history.

Behind him, Ronald Reagan is the third oldest, being 69 years old when he was sworn in in 1981. William Henry Harrison was 68 years old at the start of his presidency in 1841, and James Buchanan was 65 when his term began in 1857.