This is a list of prime ministers of Belgium by age. Where the Prime Minister in question is still living, the longevity is calculated up to July 2, 2021. Two measures of the longevity are given; this is to allow for the differing number of leap days occurring within the life of each Prime Minister. The first column is the number of days between date of birth and date of death, allowing for leap days; the second column breaks this number down into years and days, with the years being the number of whole years the Prime Minister lived, and the days being the remaining number of days after his/her last birthday.