How many weeks in a year?

In the Gregorian calendar, which is the most widely used civil calendar, the number of weeks in a year can be calculated as follows:

Common Year

A common year, which has 365 days, contains 52 weeks and 1 day. This is calculated by dividing the total number of days in the year by the number of days in a week: [ \frac{365 \text{ days}}{7 \text{ days/week}} = 52 \text{ weeks and 1 day} ]134.

Leap Year

A leap year, which has 366 days, contains 52 weeks and 2 days. This is similarly calculated: [ \frac{366 \text{ days}}{7 \text{ days/week}} = 52 \text{ weeks and 2 days} ]134.

In the context of full weeks, both common and leap years have 52 full weeks, with the additional days not constituting a full week134. However, in a leap year, these extra two days can sometimes be considered as part of a 53rd week, especially in certain week numbering systems like ISO-86015.