Perpetual Calendar and Repeating Years
Every year uses one of just 14 calendars: January 1 can fall on any of the 7 weekdays, and the year is either common or leap. The 2026 calendar (a common year starting on Thursday) was also used in 2015 and repeats in 2037.
Updated · By the YearlyCalendar.org team
The 14 calendars and their years (1940–2060)
Any two years in the same row have identical calendars: every date falls on the same weekday. The dominical letter marks the first Sunday of January (A = January 1, B = January 2 …); leap years have two letters, the second for March to December.
| # | Year type, starts on | Dominical letter | Years 1940–2060 | Per 400 years |
|---|---|---|---|---|
| 1 | Common, Sunday | A | 1950, 1961, 1967, 1978, 1989, 1995, 2006, 2017, 2023, 2034, 2045, 2051 | 43 |
| 2 | Common, Monday | G | 1945, 1951, 1962, 1973, 1979, 1990, 2001, 2007, 2018, 2029, 2035, 2046, 2057 | 43 |
| 3 | Common, Tuesday | F | 1946, 1957, 1963, 1974, 1985, 1991, 2002, 2013, 2019, 2030, 2041, 2047, 2058 | 44 |
| 4 | Common, Wednesday | E | 1941, 1947, 1958, 1969, 1975, 1986, 1997, 2003, 2014, 2025, 2031, 2042, 2053, 2059 | 43 |
| 5 | Common, Thursday | D | 1942, 1953, 1959, 1970, 1981, 1987, 1998, 2009, 2015, 2026, 2037, 2043, 2054 | 44 |
| 6 | Common, Friday | C | 1943, 1954, 1965, 1971, 1982, 1993, 1999, 2010, 2021, 2027, 2038, 2049, 2055 | 43 |
| 7 | Common, Saturday | B | 1949, 1955, 1966, 1977, 1983, 1994, 2005, 2011, 2022, 2033, 2039, 2050 | 43 |
| 8 | Leap, Sunday | AG | 1956, 1984, 2012, 2040 | 15 |
| 9 | Leap, Monday | GF | 1940, 1968, 1996, 2024, 2052 | 13 |
| 10 | Leap, Tuesday | FE | 1952, 1980, 2008, 2036 | 14 |
| 11 | Leap, Wednesday | ED | 1964, 1992, 2020, 2048 | 14 |
| 12 | Leap, Thursday | DC | 1948, 1976, 2004, 2032, 2060 | 13 |
| 13 | Leap, Friday | CB | 1960, 1988, 2016, 2044 | 15 |
| 14 | Leap, Saturday | BA | 1944, 1972, 2000, 2028, 2056 | 13 |
How often calendars repeat
| Position in the leap cycle | Example | Same calendar next in | Gap |
|---|---|---|---|
| Leap year | 2028 | 2056 | 28 years |
| Year after a leap year | 2029 | 2035 | 6 years |
| Second year after a leap year | 2026 | 2037 | 11 years |
| Year before a leap year | 2027 | 2038 | 11 years |
Within a century, a leap year's calendar returns after 28 years, and a common year's after 6 or 11 years. The pattern breaks around century years that are not leap years: the calendar of 2096 next appears in 2108 (12 years later) and that of 2097 in 2109.
The whole Gregorian calendar repeats exactly every 400 years, because 400 years contain 146,097 days, which is exactly 20,871 weeks. So 2026 has the same calendar as 1626 and 2426. Over those 400 years the 14 calendars are not equally common, as the last column of the table shows.
Reusing an old calendar
- A reused calendar has the right weekday for every date, but not the right moveable holidays. Easter 2026 is on April 5, but in 2043 it falls on March 29.
- Holidays tied to a weekday rule (Thanksgiving, Memorial Day, Labor Day) do fall on the same dates in years that share a calendar, as long as the rule itself has not changed.
- The table uses the Gregorian calendar, adopted in 1582 in Catholic countries and in 1752 in Britain and its colonies.
Frequently asked questions
What is a perpetual calendar?
A calendar that works for many years. The simplest form is a table like the one above: find a year's type (its January 1 weekday and whether it is a leap year), and any calendar of the same type shows the right weekday for every date. Mechanical versions use movable dials or blocks.
Why doesn't the calendar simply repeat every 7 years?
A common year is 52 weeks plus 1 day, so the next year starts one weekday later; after a leap year it starts two weekdays later. That extra jump in leap years breaks a 7-year pattern, so calendars repeat after 6, 11 or 28 years instead.
How can I find the weekday of a date without a calendar?
Use John Conway's Doomsday rule. In any year, 4/4, 6/6, 8/8, 10/10, 12/12, 5/9, 9/5, 7/11, 11/7, 3/14 and the last day of February fall on the same weekday, the year's “doomsday”. In 2026 it is a Saturday. Count from the nearest one: December 25 is 13 days after 12/12, so in 2026 it is a Friday.