The 53-week calendar is a variation of the Gregorian calendar that is used (mainly) in government and business for fiscal years, as well as in timekeeping. In this calendar, the year does not necessarily end on a specific day (e.g., January 31 or December 31). The year does, however, end on a day of the week (e.g., the last Friday in December). Therefore, weeks and months of equal length are allowed to exist. A year can have a total of 371 days.

This type of a calendar has also been considered as a possible calendar reform.

The ISO week is an example of such a calendar.

Advantages

• There are no variations between day of week between years for a specific date.
• The calendar starts on the same day and week every year.
• Unlike the regular calendar, there are no variations of years.
• There are no fragments of partial weeks at the end of the year.
• Unlike certain proposed calendar reforms such a the World Calendar and International Fixed Calendar, there is no need to modify the week.

Disadvantages

• The new year will vary by at least 6 days in the Gregorian calendar or any other similar calendar.
• The equinox and solstice dates will vary by at least one week.
• The rule determining whether a year has 53 weeks, will be more complicated than a leap year rule, especially if the variation of the equinox and solstice dates is less than two weeks.

External links

Leap Week Calendars This deals with various calendars of this type.