This is a list of United States Presidents by age. This table can be sorted to display United States Presidents by name, order of office, date of birth, age at ascension, length of retirement or lifespan. Age at ascension is determined by the day a president assumed office, not the day of the election. The average age is 55 years old. The youngest president to be elected to office was John F. Kennedy. The youngest to assume office was Theodore Roosevelt after William McKinleys assassination. The oldest president to assume office was Ronald Reagan. John McCain would surpass this record if he were elected president in 2008. If elected, Barack Obama would be fifth youngest elected president, just slightly older than the most recent Democratic president, Bill Clinton.

List of United States Presidents by age – Wikipedia, the free encyclopedia.