List of Presidents of the United States by age
This is a list of presidents of the United States by age. The first table charts the age of each United States president at the time of presidential inauguration (first inauguration if elected to multiple and consecutive terms), upon leaving office, and at the time of death. Each president's lifespan (age at death) is measured in two ways, to allow for the differing number of leap days that each experienced. The first figure is the number of days between the president's date of birth and date of death, allowing for leap days; in parentheses, the same period is given in years and days, with the years being the number of whole years that the president lived, and the days being the number of days since the last birthday. Where the president is still living, lifespan is calculated up to April 28, 2017. The second table includes those presidents who had the distinction among their peers of being the oldest living president, and charts both when they became and ceased to be oldest living.
The average age of accession is 55 years and 6 months, which falls between Warren G. Harding (23rd) and Benjamin Harrison (24th). The youngest person to assume office was Theodore Roosevelt, who became president following William McKinley's assassination, at the age of 42 years, 322 days. The youngest president elected to office was John F. Kennedy, who assumed office at the age of 43 years, 236 days, who was also the youngest to leave office when he was assassinated, at the age of 46 years, 177 days. The oldest president to assume office is Donald Trump, who was 70 years, 220 days old when he assumed office. Ronald Reagan was the oldest in office, at the age of 77 years, 349 days when he left office.
...
Wikipedia