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This World Calendar with Leap Week is a leap week calendar that follows a 62-year cycle with 11 leap weeks.

The year[]

The year is divided into 12 months exactly as in the World Calendar, but instead of the Leapdays and Worldsdays, which interrupt the week, there is a leap week (called Tychon) inserted between June and July in each leap year.

Leap year rule[]

The 62-year cycle begins 3 years before the year of reform, which must be a Gregorian year that begins on a Sunday (e.g. 2023). The intervals between successive leap years starting with the interval of the year of reform are

6 5 6 6 5 6 5 6 6 5 6
If the year of reform were 2023, it would result in leap years:
2026 2031 2037 2043 2048 2054 2059 2065 2071 2076 2082
and so on every 62 years

One disadvantage of the leap year rule is that it depends on the year of adoption so prevents the calendar being used straight away without any adoption date. This can be remedied by fixing the calendar as though it were adopted some year in the past, such as 1995, 2006, 2012 or 2017.


A Calendar of the future. A World Calendar with a Leap Week Josef Suran Vistas in Astronomy vol 41 No 4 pp 493-506 1998