Weeks in a common Year One calendar common year has 365 days: 1 common year = 365 days = (365 days) / (7 days/week) = 52.143 weeks = 52 weeks + 1 day
Weeks in a leap year One calendar leap year has 366 days, when February has 29 days: 1 leap year = 366 days = (366 days) / (7 days/week) = 52.286 weeks = 52 weeks + 2 days