A common year is a calendar year with 365 days, as distinguished from a

leap year A leap year (also known as an intercalary year or bissextile year) is a calendar year that contains an additional day (or, in the case of a lunisolar calendar, a month) added to keep the calendar year synchronized with the astronomical year or ...

, which has 366. More generally, a common year is one without intercalation. The

Gregorian calendar The Gregorian calendar is the calendar used in most parts of the world. It was introduced in October 1582 by Pope Gregory XIII as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years d ...

(like the earlier

Julian calendar The Julian calendar, proposed by Roman consul Julius Caesar in 46 BC, was a reform of the Roman calendar. It took effect on , by edict. It was designed with the aid of Greek mathematicians and astronomers such as Sosigenes of Alexandri ...

) employs both common years and leap years to keep the calendar aligned with the

tropical year A tropical year or solar year (or tropical period) is the time that the Sun takes to return to the same position in the sky of a celestial body of the Solar System such as the Earth, completing a full cycle of seasons; for example, the time ...

, which does not contain an exact number of days. The common year of 365 days has 52

week A week is a unit of time equal to seven days. It is the standard time period used for short cycles of days in most parts of the world. The days are often used to indicate common work days and rest days, as well as days of worship. Weeks are of ...

s and one day, hence a common year always begins and ends on the same day of the week (for example, January 1 fell on a Saturday and December 31 will fall on a Saturday in 2022, the current year) and the year following a common year will start on the subsequent day of the week. In common years, February has exactly four weeks, so March begins on the same day of the week. November also begins on this day. For example, February 2022 started on a Tuesday, so March started on a Tuesday as well. November follows the same characteristic. Each common year has 179 even-numbered days and 186 odd-numbered days. In the Gregorian calendar, 303 of every 400 years are common years. By comparison, in the

, 300 out of every 400 years are common years, and in the Revised Julian calendar (used by Greece) 682 out of every 900 years are common years.

Calendars

* Common year starting on Monday *

Common year starting on Tuesday A common year starting on Tuesday is any non-leap year (i.e. a year with 365 days) that begins on Tuesday, 1 January, and ends on Tuesday, 31 December. Its dominical letter hence is F. The most recent year of such kind was 2019 and the next one ...

* Common year starting on Wednesday *

Common year starting on Thursday A common year starting on Thursday is any non-leap year (i.e. a year with 365 days) that begins on Thursday, 1 January, and ends on Thursday, 31 December. Its dominical letter hence is D. The most recent year of such kind was 2015 and the next ...

Common year starting on Friday A common year starting on Friday is any non-leap year (i.e. a year with 365 days) 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 wi ...

* Common year starting on Saturday *

Common year starting on Sunday A common year starting on Sunday is any non-leap year (i.e. a year with 365 days) that begins on Sunday, January 1, 1 January, and ends on Sunday, December 31, 31 December. Its dominical letter hence is A. The most recent year was 2017 and the next ...

Calendars Types of year Units of time {{time-stub