List of calendars

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Further information: Calendar era

This is a list of calendars. Included are historical calendars as well as proposed ones. Historical calendars are often grouped into larger categories by cultural sphere or historical period; thus O'Neil (1976) distinguishes the groupings Egyptian calendars (Ancient Egypt), Babylonian calendars (Ancient Mesopotamia), Indian calendars (Hindu and Buddhist traditions of the Indian subcontinent), Chinese calendars and Mesoamerican calendars. These are not specific calendars but series of historical calendars undergoing reforms or regional diversification.

In Classical Antiquity, the Hellenic calendars inspired the Roman calendar, including the solar Julian calendar introduced in 45 BC. Many modern calendar proposals, including the Gregorian calendar itself, are in turn modifications of the Julian calendar.

List of calendars[edit]

In the list below, specific calendars are given, listed by calendar type (solar, lunisolar or lunar), time of introduction (if known), context of use and cultural or historical grouping (if applicable).

Regional or historical groups: Egyptian, Mesopotamian, Iranian, Hindu, Buddhist, Pre-Columbian Mesoamerican Hellenic, Julian or Gregorian-derived.

Calendars fall into three types, lunisolar, solar and lunar, besides calendars with "years" of fixed length, with no intercalation. Most pre-modern calendars are lunisolar. The Islamic and some Buddhist calendars are lunar, while most modern calendars are solar, based on either the Julian or the Gregorian calendars.

Some "calendars" listed are identical to the Gregorian calendar except for substituting regional month names and/or using a different calendar era. For example, the Thai solar calendar (introduced 1888) is the Gregorian calendar using a different era (543 BC) and different names for the Gregorian months (Thai names based on the signs of the zodiac).

Name type group introduction usage comments
Egyptian calendar fixed (365 days) Egyptian Bronze Age Middle Kingdom The year is based on the heliacal rising of Sirius (Sothis) and divided into the three seasons of akhet (Inundation), peret (Growth) and shemu (Harvest). The heliacal rising of Sothis returned to the same point in the calendar every 1,460 years (a period called the Sothic cycle).[1]
Umma calendar lunisolar Mesopotamian Bronze Age Sumer/Mesopotamia Recorded in Neo-Sumerian records (21st century BC), presumably based on older (Ur III) sources.
Pentecontad calendar solar Mesopotamian Bronze Age Amorites A Bronze Age calendar in which the year is divided into seven periods of fifty days, with an annual supplement of fifteen or sixteen days for synchronisation with the solar year.
Five Phases (五行曆) lunisolar Chinese Bronze Age(?) China
Roman Republican calendar solar Roman 713 BC Roman Republic Based on the reforms introduced by Numa Pompilius in c. 713 BC.
Six Ancient Calendars (古六曆) lunisolar Chinese Iron Age China Six classical (Zhou era) calendars: Huangdi (黃帝曆), Zhuanxu (顓頊曆), Xia (夏曆), Yin (殷曆), Zhou's calendar (周曆) and Lu (魯曆).
Haab' fixed (365 days) Pre-Columbian (Maya) 1st millennium BC[citation needed] Maya
Tzolk'in fixed (260 days) Pre-Columbian (Maya) 1st millennium BC[citation needed] Maya
Xiuhpohualli fixed (365 days) Pre-Columbian (Aztec) [citation needed] Aztecs
Tonalpohualli fixed (260 days) Pre-Columbian (Aztec) [citation needed] Aztecs
Attic calendar lunisolar Hellenic 6th century BC Classical Athens
Old Persian calendar lunisolar(?) Iranian 4th century BC(?) Persian Empire Based on earlier Babylonian/Mesopotamian models
Seleucid calendar lunisolar Hellenic/Babylonian 4th century BC Seleucid Empire Combination of the Babylonian calendar, ancient Macedonian (Hellenic) month names and the Seleucid era.
Qin calendar (秦曆) lunisolar Chinese Qin dynasty China Based on the Zhuanxu and Xia calendars.
Grand Inception Calendar (太初曆) lunisolar Chinese Han dynasty China Introduced the "no zhongqi" rule for inserting leap months; based on a solar year of 3653851539 days and a lunar month of 294381 days.
Ptolemaic calendar lunisolar Egyptian 238 BC Ptolemaic Egypt The Canopic reform of 238 BC introduced the leap year every fourth year later adopted in the Julian calendar. The reform eventually went into effect with the introduction of the "Alexandrian calendar" (or Julian calendar) by Augustus in 26/25 BC, which included a 6th epagomenal day for the first time in 22 BC.
Julian calendar solar Roman 45 BC Western World Revision of the Roman Republican calendar, in use in the Roman Empire and the Christian Middle Ages, and remains in use as liturgical calendar of Eastern Orthodox Churches.
Coptic calendar solar Egyptian 1st century[citation needed] Coptic Orthodox Church Based on both the Ptolemaic calendar and the Julian calendar
Ethiopian calendar solar Egyptian 1st century[citation needed] Ethiopia, Ethiopian Christians the calendar associated with Ethiopian Church, based on the Coptic calendar
Qumran calendrical texts fixed (364 days) c. 1st century[citation needed] Second Temple Judaism Description of a division of the year into 364 days, also mentioned in the pseudepigraphical Book of Enoch (the "Enoch calendar").
Gaulish calendar lunisolar Iron Age Gauls/Celts Early calendars used by Celtic peoples prior to the introduction of the Julian calendar, reconstruction mostly based on the Coligny calendar (2nd century), which may be partially influenced by the Julian calendar.
Zoroastrian calendar fixed (365 days) Iranian 3rd century Sassanid Persia Based on both the Old Persian and Seleucid (Hellenic) calendars. Introduced in AD 226, reformed in AD 272, and again several times in the 5th to 7th centuries.
Dàmíng Calendar (大明曆) lunisolar Chinese 510 China Created by Zu Chongzhi, most accurate calendar in the world at its invention
Japanese calendar lunisolar Chinese-derived 6th century Japan umbrella term for calendars historically and currently used in Japan, in the 6th century derived from the Chinese calendar
Wùyín Yuán Calendar (戊寅元曆) lunisolar Chinese 619 China First Chinese calendar to use the true motion of the moon
Islamic calendar lunar 632 Islam Based on the observational lunisolar calendars used in Pre-Islamic Arabia. Remains in use for religious purposes in the Islamic world.
Pyu calendar lunisolar Hindu/Buddhist-derived 640[dubious ] mainland Southeast Asia Traditional calendar of Southeast Asia, in use until the 19th century. Traditionally said to originate in 640 (the calendar era) in Sri Ksetra Kingdom, one of the Burmese Pyu city-states.
Nepal Sambat lunar Buddhist 9th century Nepal A lunar Buddhist calendar traditional to Nepal, recognition in Nepal in 2008.
Byzantine calendar solar Julian 988 Ecumenical Patriarchate of Constantinople Julian calendar with Anno Mundi era in use c. 691 to 1728.
Armenian calendar fixed (365 days) Iranian medieval[citation needed] medieval Armenia Calendar used in medieval Armenia and as liturgical calendar of the Armenian Apostolic Church. Derived from the Zoroastrian (or related medieval Iranian calendars such as the Sogdian/Choresmian ones[2]). It uses the era AD 552. In modern Armenian nationalism, an alternative era of 2492 BC is sometimes used.
Bulgar calendar solar(?) Turkic/Chinese-derived medieval Volga Bulgaria A reconstruction based on a short 15th century transcript in Church Slavonic originally proposed by Finnish Slavist Jooseppi Julius Mikkola in 1913. According to the reconstructed calendar, the Bulgars used a 12-year cyclic calendar similar to the one adopted by other Turkic peoples from the Chinese calendar.
Florentine calendar solar Julian medieval Republic of Florence Variant of the Julian calendar in use in medieval Florence
Pisan calendar solar Julian medieval Republic of Pisa Variant of the Julian calendar in use in medieval Pisa
Tamil calendar solar Hindu medieval[clarification needed] Tamil Nadu The Hindu calendar used in Tamil Nadu
Nepali calendar solar Hindu medieval[clarification needed] Nepal One of the Hindu calendars
Bengali calendar solar Hindu medieval[clarification needed] Bengal, Bangladesh One of the Hindu calendars, in Bangladesh revised in 1987.
Thai lunar calendar lunisolar Hindu/Buddhist[clarification needed] medieval[clarification needed] Thailand A Buddhist calendar
Pawukon calendar fixed (210 days) Hindu [citation needed] Bali
Old Icelandic calendar solar 10th century medieval Iceland partly inspired by the Julian calendar and partly by older Germanic calendar traditions. Leap week calendar based on a year of 364 days.
Jalali calendar solar Iranian 1079 Seljuk Sultanate A calendar reform commissioned by Sultan Jalal al-Din Malik Shah I
Hebrew calendar lunisolar Babylonian/Seleucid-derived 11th/12th century Judaism recorded by Maimonides in the Mishneh Torah, resulting from various reforms and traditions developing since Late Antiquity. The Anno Mundi era gradually replaced the Seleucid era in Rabbinical literature in the 11th century.
Tibetan calendar lunisolar Buddhist 13th century Tibet The Kalacakra, a Buddhist calendar introduced in 13th-century Tibet
Shòushí Calendar (授时曆) solar Chinese 1281 China Based on a solar year of 365.2425 (equal to the Gregorian year)
Runic calendar solar Julian 13th century Sweden A written representation of the Metonic cycle used in medieval and early modern Sweden, allowing to calculate the dates of the full moons relative to the Julian date. The introduction of the Gregorian calendar in Sweden in 1753 rendered the runic calendars unusable.
Incan calendar lunisolar Pre-Columbian 15th century Inca Empire
Chula Sakarat lunisolar Burmese 16th century Southeast Asia
Gregorian calendar solar Julian-derived 1582 worldwide Introduced as a reform of the Julian calendar in the Roman Catholic church, since the 20th century in de facto use worldwide.
Javanese calendar lunar Islamic influenced 1633 Java Based on the Hindu calendar using the Saka era (78 CE), but changed to the lunar year following the Islamic calendar.
Swedish calendar solar Julian-derived 1700 Sweden Part of the controversy surrounding the adoption of the Gregorian calendar, in use 1700–1844.
Astronomical year numbering solar Julian-derived 1740 astronomy A mixture of Julian and Gregorian calendar, giving dates before 1582 in the Julian calendar, and dates after 1582 in the Gregorian calendar, counting 1 BC as year zero, and negative year numbers for 2 BC and earlier.
French Republican Calendar solar Gregorian 1793 First French Republic In use in revolutionary France 1793 to 1805.
Pancronometer solar Gregorian 1745 Universal Georgian Calendar proposed by Hugh Jones
Rumi calendar solar Julian 1839 Ottoman Empire Julian calendar using the Hijri era introduced in the Ottoman Empire.
Positivist calendar solar Gregorian 1849 solar calendar with 13 months of 28 days.
Bahá'í calendar solar[3] Gregorian (formerly)[4] 1873 Bahá'í Uses a year of 19 months of 19 days each and a 1844 era.
Thai solar calendar solar Gregorian 1888 Thailand The Gregorian calendar but using the Buddhist Era (543 BC)
Invariable Calendar solar Gregorian 1900 Gregorian calendar with four 91-day quarters of 13 weeks
International Fixed Calendar solar Gregorian 1902 A "perpetual calendar" with a year of 13 months of 28 days each.
Minguo calendar solar Gregorian 1912 Republic of China Variant of the Gregorian calendar introduced in Taiwan in 1912.
Revised Julian calendar solar Julian-derived 1923 In use by some Orthodox churches
Solar Hijri calendar solar Iranian/Islamic 1925 Iran, Afghanistan New Year is the day of the astronomical vernal equinox. The calendar as introduced in 1925 revived Iranian month names but counted the years of the Hijri era. The era was changed in 1976 to 559 BC (reign of Cyrus the Great), but was reverted to the Hijri era after the Iranian Revolution.
Soviet calendar solar Gregorian 1929 Soviet Union Gregorian calendar with 5- and 6-day weeks, used during 1929 to 1940.
World Calendar solar Gregorian 1930
Pax Calendar solar Gregorian 1930 Leap week calendar
Pataphysical calendar solar Gregorian 1949 Absurdist variant of the Gregorian calendar by Alfred Jarry.
Shire calendar lunisolar Germanic 1955 Tolkien fandom A reconstruction of the Anglo-Saxon calendar used in the fictional context of The Lord of the Rings
Indian national calendar solar Gregorian-derived 1957 Republic of India Gregorian calendar with months based in traditional Hindu calendars and numbering years based on the Saka era (AD 78).
Assyrian calendar lunar Babylonian 1950s Assyrianism Lunar calendar with an "Assyrian era" of 4750 BC, introduced in Assyrian nationalism in the 1950s
Discordian calendar solar Gregorian 1963 Discordianism Calendar invented in the context of the absurdist or parody religion of Discordianism, Gregorian calendar variant with a year consisting of five 73-day seasons.
World Season Calendar solar Gregorian 1973 Dividing the year into four seasons.
Dreamspell solar Mesoamerican-derived 1987 Esotericism Inspired by the fixed-length Mayan calendars but with a system of leap years.
Tranquility Calendar solar Gregorian 1989 modification of the International Fixed Calendar
Holocene calendar solar Gregorian 1993 The Gregorian calendar with the era shifted by 10,000 years.
Juche era calendar solar Gregorian 1997 North Korea Gregorian calendar with the era 1912 (birth of Kim Il-sung)
Nanakshahi calendar solar Gregorian-derived 1998 Sikhism Gregorian calendar with months based in traditional Hindu calendars and numbering years based on the era 1469.
Symmetry454 solar Gregorian 2004 Leap week calendar
Hanke-Henry Permanent Calendar solar Gregorian 2004 Leap week calendar, revised in 2011
Igbo calendar (?) 2009(?) Igbo people(?) A 2009 proposal (Angelicus M. B. Onasanya, The Urgency of Now!: Building a True Nigerian Nation) based in Igbo tradition, with a year of 13 lunar months, with 28-day lunar months divided into seven 4-day periods, plus leap days.

Variant month names[edit]

Regional or historical names for lunations or Julian/Gregorian months

Tradition culture comments
Germanic calendar Germanic Medieval records of Germanic names of lunar months later equated with the Julian months.
Berber calendar Berber reconstructed medieval Berber-language names of the Julian months used in pre-Islamic (Roman era) North Africa
Lithuanian calendar Lithuania Lithuanian names for the Gregorian months and days of the week, officially recognized in 1918.
Rapa Nui calendar Easter Islands Thirteen names of lunar months recorded in the 19th century.
Xhosa calendar Xhosa people [clarification needed]
Turkmen Turkmenistan Turkmen names officially adopted in 2002 following Ruhnama by president-for-life Saparmurat Niyazov.
Hellenic calendars Hellenistic Greece A great variety of regional month names in Ancient Greece, mostly attested in the 2nd century BC.

Non-standard weeks[edit]

Further information: Week and Eight-day week
Tradition week length comments
Bali various
Korea 5 days [citation needed]
Java 5 days [citation needed]
Discordian 5 days
Akan 6 days A traditional "six-day week" which combined with the Gregorian seven-day week gave rise to a 42-day cycle.
Ancient Rome 8 days The Roman nundinal cycle.
Burmese 8 days
Celtic 8 days reconstructed.[5][6]
Baltic 9 days Linguistic reconstruction[citation needed]
Chinese 10 days
French Republican Calendar 10 days
Aztecs 13 days Trecena, division of the Tonalpohualli 260-day period

Calendaring and timekeeping standards[edit]

  • Coordinated Universal Time, adopted 1960 and since 1972 including a system of observation-based leap seconds.
  • ISO 8601, standard based on the Gregorian calendar, Coordinated Universal Time and ISO week date, a leap week calendar system used with the Gregorian calendar
  • Fiscal year varies with different countries. Used in accounting only.
  • 360-day calendar used for accounting
  • 365-day calendar used for accounting
  • Unix time, number of seconds elapsed since 1 January 1970, 00:00:00 (UTC).
  • Julian day, number of days elapsed since 1 January 4713 BC, 12:00:00 (UTC).
  • Heliocentric Julian Date, Julian day corrected for differences in the Earth's position with respect to the Sun.
  • Barycentric Julian Date, Julian day corrected for differences in the Earth's position with respect to the barycentre of the Solar System.
  • Lilian date, number of days elapsed since the beginning of the Gregorian Calendar on 15 October 1582.
  • Rata Die, number of days elapsed since 1 January 1 AD 1 in the proleptic Gregorian calendar.

Non-Earth or fictional[edit]

See also[edit]


  1. ^ Parker, Richard A., "The Calendars of Ancient Egypt", Studies in Ancient Oriental Civilization, 26. Chicago: University of Chicago Press, 1950.
  2. ^ Stern (2012) p. 179
  3. ^ Despite being a solar calendar, two Holy Days are determined by lunar months.
  4. ^ Until 2014, leap years were tied to the Gregorian calendar, with new year always starting on Gregorian March 20, but since 21 March 2015 the Bahá'í calendar is no longer locked to the Gregorian calendar and the new year now always starts on the day of the vernal equinox.
  5. ^ Rhys (1840-1915), Sir John (1892). Lectures on the Origin and Growth of Religion as Illustrated by Celtic Heathendom. pp. 360–382. 
  6. ^ The Welsh people: chapters on their origin, history, laws, language ... - Sir John Rhys, Sir David Brynmor Jones - Google Books. p. 220. Retrieved 2012-10-22. 
  • Brian Williams, Calendars, Cherrytree Books, 2002.
  • Frank Parise, The Book of Calendars, Gorgias Press LLC, 2002.
  • Sacha Stern, Calendars in Antiquity: Empires, States, and Societies, OUP Oxford, 2012.
  • William Matthew O'Neil, Time and the Calendars, Manchester University Press, 1976.
  • Anthony F. Aveni, Empires of Time: Calendars, Clocks and Cultures, Tauris Parke Paperbacks, 2000.