Century common year

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A century common year is a common year in the Gregorian calendar that is divisible by 100 but not by 400. Like all common years, these years do not get an extra day in February, meaning they have 365 days instead of 366. These years are the only common years that are divisible by 4.

In the obsolete Julian Calendar, all years that were divisible by 4 were leap years, meaning no century years could be common years. However, this rule adds too many leap days, resulting in the calendar drifting with respect to the seasons, which is the same thing that would happen if there were no leap years at all. So, in 1582, Pope Gregory XIII introduced a slightly modified version of the Julian Calendar, the Gregorian Calendar, where century years would not be leap years if they are not divisible by 400. Therefore, 1700 is the first century year in the Gregorian Calendar being a common year. The years 1800 and 1900 were also century common years, and so will 2100, 2200, 2300, 2500, 2600, 2700, 2900, and 3000.

The Gregorian Calendar repeats itself every 400 years, so century common years start on a Friday if the remainder obtained when dividing the year by 400 is 100 (dominical letter C), Wednesday if the remainder is 200 (dominical letter E), and Monday if the remainder is 300 (dominical letter G). This means that century leap years always begin on a Saturday (dominical letter BA).

In most school districts, if you don't graduate from elementary school in a year that is not a leap year there will be two leap days between when you graduate from elementary school and when you graduate from high school instead of one unless if you are in middle school or high school in a year that is divisible by 100 but not by 400.


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A leap year is a calendar year that contains an additional day compared to a common year. The 366th day is added to keep the calendar year synchronised with the astronomical year or seasonal year. Since astronomical events and seasons do not repeat in a whole number of days, calendars having a constant number of days each year will unavoidably drift over time with respect to the event that the year is supposed to track, such as seasons. By inserting ("intercalating") an additional day—a leap day—or month—a leap month—into some years, the drift between a civilization's dating system and the physical properties of the Solar System can be corrected.

The Revised Julian calendar, or less formally the new calendar and also known as the Milanković calendar, is a calendar proposed in 1923 by the Serbian scientist Milutin Milanković as a more accurate alternative to both Julian and Gregorian calendars. At the time, the Julian calendar was still in use by all of the Eastern Orthodox Church and affiliated nations, while the Catholic and Protestant nations were using the Gregorian calendar. Thus, Milanković's aim was to discontinue the divergence between the naming of dates in Eastern and Western churches and nations. It was intended to replace the Julian calendar in Eastern Orthodox Churches and nations. From 1 March 1600 through 28 February 2800, the Revised Julian calendar aligns its dates with the Gregorian calendar, which had been proclaimed in 1582 by Pope Gregory XIII.

A common year starting on Sunday is any non-leap year that begins on Sunday, 1 January, and ends on Sunday, 31 December. Its dominical letter hence is A. The most recent year of such kind was 2023 and the next one will be 2034 in the Gregorian calendar, or, likewise, 2018 and 2029 in the obsolete Julian calendar, see below for more.

A common year starting on Friday is any non-leap year that begins on Friday, 1 January, and ends on Friday, 31 December. Its dominical letter hence is C. The most recent year of such kind was 2021 and the next one will be 2027 in the Gregorian calendar, or, likewise, 2022 and 2033 in the obsolete Julian calendar; see below for more. This common year is one of the three possible common years in which a century year can end on, and occurs in century years that yield a remainder of 100 when divided by 400. The most recent such year was 1700 and the next one will be 2100.

A common year starting on Monday is any non-leap year that begins on Monday, 1 January, and ends on Monday, 31 December. Its dominical letter hence is G. The most recent year of such kind was 2018 and the next one will be 2029 in the Gregorian calendar, or likewise, 2019 and 2030 in the Julian calendar, see below for more. This common year is one of the three possible common years in which a century year can begin on and occurs in century years that yield a remainder of 300 when divided by 400. The most recent such year was 1900 and the next one will be 2300.

<span class="mw-page-title-main">Date of Easter</span>

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A common year starting on Saturday is any non-leap year that begins on Saturday, 1 January, and ends on Saturday, 31 December. Its dominical letter hence is B. The most recent year of such kind was 2022 and the next one will be 2033 in the Gregorian calendar or, likewise, 2023 and 2034 in the obsolete Julian calendar. See below for more.

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