Except for when the 28-year cycle is disrupted by a non-leap century year, the rules are as follows.
A leap year will repeat itself after 28 years.
The first year after a leap year repeats in a 6-11-11 pattern. This means it will repeat after 6 years, then after 17 years, and then after 28 years.
The second year after a leap year repeats in a 11-6-11 pattern. This means it will repeat after 11 years, then after 17 years, and then after 28 years.
The third year after a leap year repeats in a 11-11-6 pattern. This means it will repeat after 11 years, then after 22 years, and then after 28 years.
As of 2018, the next time you can use a 1998 calendar again is in 2026.
As of 2018, the next time you can use a 1987 calendar is in 2026.
The year 1968 was a leap year starting on Monday. As of 2010, the next three occasions in which you can use this calendar are 2024, 2052, and 2080.
The calendar of 1998 will repeat in the year 2029. This is because there is a 11-year cycle for calendars to repeat. In this cycle, the days of the week for a particular date will match up again after 11 years. Therefore, the calendar of 1998 will align with the calendar of 2029.
The Gregorian calendar is the calendar that we are currently using.1 year : 365 days1 leap year: 366 daysMonday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday.