List of calendars

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 introduced in 1582 AD, contains modifications from that of the Julian calendar.

List of calendars

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

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

Calendars fall into four types, lunisolar, solar, lunar, seasonal, besides calendars with "years" of fixed length, with no intercalation. Most pre-modern calendars are lunisolar. The seasonal calendars rely on changes in the environment rather than lunar or solar observations. 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 or using a different calendar epoch. For example, the Thai solar calendar (introduced 1888) is the Gregorian calendar using a different epoch (543 BC) and different names for the Gregorian months (Thai names based on the signs of the zodiac).

Vikram samwatLunisolarIndianAncient IndiaIndia/NepalThe Vira Nirvana Samvat (era) is a calendar era beginning on 7 October 527 BCE. It commemorates the Nirvana of Lord Mahaviraswami, the 24th Jain Tirthankara. This is one of the oldest system of chronological reckoning which is still used in India.
Egyptian calendarfixed (365 days)EgyptianBronze AgeMiddle KingdomThe 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 calendarlunisolarMesopotamianBronze AgeSumer/MesopotamiaRecorded in Neo-Sumerian records (21st century BC), presumably based on older (Ur III) sources.
Pentecontad calendarsolarMesopotamianBronze AgeAmoritesA 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.
Four Seasons and Eight NodessolarChineseBronze Age(?)ChinaThe years is divided into four seasons, and each season is divided into a festival and three months. The start and middle of each season is the key node of the year.
Gezer CalendarlunarMesopotamian1000 BCIsrael/CanaanThe years are divided into monthly or bi-monthly periods and attributes to each a duty such as harvest, planting, or tending specific crops.
Roman calendarlunisolarRoman713 BCRoman RepublicBased on the reforms introduced by Numa Pompilius in c. 713 BC.
Six Ancient CalendarslunisolarChineseIron AgeChinaSix classical (Zhou era) calendars: Huangdi, Zhuanxu, Xia, Yin, Zhou's calendar and Lu.
Nisg̱a'aseasonal / lunisolarIndigenous North AmericaNisg̱a'aThe Nisga’a calendar revolves around harvesting of foods and goods used. The original year followed the various moons throughout the year.
HaidalunarIndigenous North AmericaHaidaThe Haida calendar is a lunar calendar broken into two seasons (winter and summer) of six months each with an occasional thirteenth month between seasons.
InuitseasonalIndigenous North AmericaInuitThe Inuit calendar is based on between six and eight seasons as solar and lunar timekeeping methods do not work in the polar regions.
Haab'fixed (365 days)Pre-Columbian (Maya)1st millennium BCMaya
Tzolk'infixed (260 days)Pre-Columbian (Maya)1st millennium BCMaya
Xiuhpohuallifixed (365 days)Pre-Columbian (Aztec)Aztecs
Tonalpohuallifixed (260 days)Pre-Columbian (Aztec)Aztecs
Attic calendarlunisolar (354/ 384 days)Hellenic6th century BCClassical AthensThe year begins with the new moon after the summer solstice. It was introduced by the astronomer Meton in 432 BC. Reconstructed by Academy of Episteme.
Old Persian calendarlunisolar(?)Iranian4th century BC(?)Persian EmpireBased on earlier Babylonian/Mesopotamian models
Seleucid calendarlunisolarHellenic/Babylonian4th century BCSeleucid EmpireCombination of the Babylonian calendar, ancient Macedonian (Hellenic) month names and the Seleucid era.
Genesis CalendarlunisolarChineseHan dynastyChinaIntroduced the "month without mid-climate is intercalary" rule; based on a solar year of 3653851539 days and a lunar month of 294381 days (19 years=235 months=69396181 days).
Ptolemaic calendarlunisolarEgyptian238 BCPtolemaic EgyptThe 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 calendarsolarRoman45 BCWestern WorldRevision 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 calendarsolarEgyptian1st centuryCoptic Orthodox ChurchBased on both the Ptolemaic calendar and the Julian calendar
Ge'ez calendarsolarEthiopian1st centuryEthiopia, Ethiopian Christians, Eritrea, Eritrean Christiansthe calendar associated with Ethiopian and Eritrean Churchs, based on the Coptic calendar
Berber calendarsolarJulianIn Roman timesNorth AfricaJulian calendar used for agricultural work.
Qumran calendrical textsfixed (364 days)c. 1st centurySecond Temple JudaismDescription of a division of the year into 364 days, also mentioned in the pseudepigraphical Book of Enoch (the "Enoch calendar").
Gaulish calendarlunisolarGauls/Celts (no longer in use)Iron AgeGauls/CeltsEarly 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 calendarfixed (365 days)Iranian3rd centurySassanid PersiaBased 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.
Chinese Calendar, Dàmíng originlunisolarChinese510ChinaCreated by Zu Chongzhi, most accurate calendar in the world at its invention
Japanese calendarlunisolarChinese-derived6th centuryJapanUmbrella term for calendars historically and currently used in Japan, in the 6th century derived from the Chinese calendar
Chinese Calendar, Wùyín originlunisolarChinese619ChinaFirst Chinese calendar to use the true moon motion
Islamic calendarlunarMuslim632IslamBased on the observational lunisolar calendars used in Pre-Islamic Arabia. Remains in use for religious purposes in the Islamic world.
Pyu calendarlunisolarHindu/Buddhist-derived640mainland Southeast AsiaTraditional 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 SambatlunarBuddhist/ Hindu9th centuryNepalA lunar Buddhist calendar traditional to Nepal, recognition in Nepal in 2008.
Byzantine calendarsolarJulian988Ecumenical Patriarchate of ConstantinopleJulian calendar with Anno Mundi era in use c. 691 to 1728.
Armenian calendarfixed (365 days)Iranianmedievalmedieval ArmeniaCalendar 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 calendarsolarBulgarianBronze AgeVolga BulgariaA reconstruction based on a short 15th-century transcript in Church Slavonic called Nominalia of the Bulgarian Khans, which contains 10 pairs of calendar terms.
Florentine calendarsolarJulianmedievalRepublic of FlorenceVariant of the Julian calendar in use in medieval Florence
Pisan calendarsolarJulianmedievalRepublic of PisaVariant of the Julian calendar in use in medieval Pisa
Tamil calendarsolarHinduAncientTamil NaduThe Hindu calendar used in Tamil Nadu
Nepali calendarsolarHindu/ BuddhistmedievalNepalOne of the Hindu calendars
Bengali calendarlunisolarBengalimedievalBengalRevised in 1987.
Thai lunar calendarlunisolarHindu/BuddhistmedievalThailandA Buddhist calendar
Pawukon calendarfixed (210 days)HinduBali
Old Icelandic calendarsolar10th centurymedieval Icelandpartly inspired by the Julian calendar and partly by older Germanic calendar traditions. Leap week calendar based on a year of 364 days.
Jalali calendarsolarIranian1079Seljuk SultanateA calendar reform commissioned by Sultan Jalal al-Din Malik Shah I
Hebrew calendarlunisolarBabylonian/Seleucid-derived11th/12th centuryJudaismrecorded 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 calendarlunisolarBuddhist/Chinese-derived13th centuryTibetThe Kalacakra, a Buddhist calendar introduced in 13th-century Tibet
Seasonal InstructionsolarChinese1281ChinaBased on a solar year of 365.2425 (equal to the Gregorian year)
Runic calendarsolarJulian13th centurySwedenA 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.
Six Imperial Calendars (ß)solarChineseMing dynastyChinaIn use 1368-1644
Incan calendarlunisolarPre-Columbian15th centuryInca Empire
Muisca calendarlunisolarPre-Columbian15th centuryMuiscaComplex lunisolar calendar with three different years, composed of months divided into thirty days. After the Spanish conquest of the Muisca Confederation in present-day central Colombia in 1537 first replaced by the European Julian and as of 1582 the Gregorian calendar.
Chula SakaratlunisolarBurmese16th centurySoutheast Asia
Gregorian calendarsolarJulian-derived1582worldwideIntroduced as a reform of the Julian calendar in the Roman Catholic church, since the 20th century in de facto use worldwide.
Javanese calendarlunarIslamic influenced1633JavaBased on the Hindu calendar using the Saka era (78 CE), but changed to the lunar year following the Islamic calendar.
Seasonal ConstitutionsolarChinese1645ChinaFirst Chinese Calendar to use the true motion of the sun.
Swedish calendarsolarJulian-derived1700SwedenPart of the controversy surrounding the adoption of the Gregorian calendar, in use 1700–1712.
Astronomical year numberingsolarJulian-derived1740astronomyA 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 CalendarsolarGregorian1793First French RepublicIn use in revolutionary France 1793 to 1805.
PancronometersolarGregorian1745Universal Georgian Calendar proposed by Hugh Jones
Rumi calendarsolarJulian1839Ottoman EmpireJulian calendar using the Hijri era introduced in the Ottoman Empire.
Positivist calendarsolarGregorian1849solar calendar with 13 months of 28 days.
Badí‘ calendarsolarBaháʼí1873BaháʼíUses a year of 19 months of 19 days each and a 1844 era. Also known as the "Baháʼí Calendar" or the "Wondrous Calendar".
Thai solar calendarsolarGregorian1888ThailandThe Gregorian calendar but using the Buddhist Era (543 BC)
Invariable CalendarsolarGregorian1900Gregorian calendar with four 91-day quarters of 13 weeks
International Fixed CalendarsolarGregorian1902A "perpetual calendar" with a year of 13 months of 28 days each.
Minguo calendarsolarGregorian1912Republic of ChinaMonths and days use the Gregorian calendar, introduced in China in 1912.
Revised Julian calendarsolarJulian-derived1923some Orthodox churchescurrently synchronized with the Gregorian calendar, but different leap rule and cycle (900 years), also called Meletian calendar or Milanković calendar, after Serbian scientist Milutin Milanković who developed it.
Solar Hijri calendarsolarIranian/Islamic1925Iran, AfghanistanNew 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.
Era FascistasolarGregorian1926ItalyEpoch is 29 October 1922; in use from 1926–1943
Soviet calendarsolarGregorian1929Soviet UnionGregorian calendar with 5- and 6-day weeks, used during 1929 to 1940.
World CalendarsolarGregorian1930Perpetual calendar with 1–2 off-week days, preferred and almost adopted by the United Nations in 1950s
Pax CalendarsolarGregorian1930Leap week calendar
Pataphysical calendarsolarGregorian1949Absurdist variant of the Gregorian calendar by Alfred Jarry.
Indian national calendarsolarGregorian-derived1957Republic of IndiaGregorian calendar with months based in traditional Hindu calendars and numbering years based on the Saka era (AD 78).
Assyrian calendarlunarBabylonian1950sAssyrianismLunar calendar with an "Assyrian era" of 4750 BC, introduced in Assyrian nationalism in the 1950s
Discordian calendarsolarGregorian1963DiscordianismCalendar 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 CalendarsolarGregorian1973Divides the year into four seasons.
Dreamspelllunar/solar galacticMayan1990esotericism13 months of 28 days each, synchronized with the Maya 260-day Tzolkin, calibrated to the Chilam Balam timing systems
Tranquility CalendarsolarGregorian1989Modification of the International Fixed Calendar, starting with moon landing on 20 July 1969[3]
Holocene calendarsolarGregorian1993The Gregorian calendar with the era shifted by 10,000 years.
Juche era calendarsolarGregorian1997North KoreaGregorian calendar with the era 1912 (birth of Kim Il-sung)
Nanakshahi calendarsolarGregorian-derived1998SikhismGregorian calendar with months based in traditional Hindu calendars and numbering years based on the era 1469.
Symmetry454solarGregorian2004Leap week calendar with 4:5:4 weeks per month
Hanke-Henry Permanent CalendarsolarGregorian2004Leap week calendar with 30:30:31 days per month, revised in 2011 and 2016
Igbo calendarlunarIndigenous West African2009Igbo peopleProposal[4] based in Igbo tradition dating back to 13th century, 13 lunar months of 28 days divided into seven 4-day periods, plus leap days.

Variant month names

Regional or historical names for lunations or Julian/Gregorian months

Germanic calendarGermanicMedieval records of Germanic names of lunar months later equated with the Julian months.
Berber calendarBerberreconstructed medieval Berber-language names of the Julian months used in pre-Islamic (Roman era) North Africa
Lithuanian calendarLithuaniaLithuanian names for the Gregorian months and days of the week, officially recognized in 1918.
Rapa Nui calendarEaster IslandsThirteen names of lunar months recorded in the 19th century.
Xhosa calendarXhosa people
TurkmenTurkmenistanTurkmen names officially adopted in 2002 following Ruhnama by president-for-life Saparmurat Niyazov.
Hellenic calendarsHellenistic GreeceA great variety of regional month names in Ancient Greece, mostly attested in the 2nd century BC.
Slavic calendarSlavicLocal month names in various Slavic countries, based on weather patterns and conditions, and agricultural activities that take place in each respective month.
Romanian calendarRomania and MoldovaTraditional names for the twelve months of the Gregorian calendar, which are usually used by the Romanian Orthodox Church.

Non-standard weeks

Traditionweek lengthcomments
Korea5 days
Java - (Pasaran)5 days
Discordian5 days
Akan6 daysA traditional "six-day week" which combined with the Gregorian seven-day week gave rise to a 42-day cycle.
Ancient Rome8 daysThe Roman nundinal cycle.
Burmese8 days
Celtic8 daysreconstructed.[5][6]
Baltic9 daysLinguistic reconstruction; the Gediminas Sceptre indicated that a week lasted for nine days during King Gediminas' reign.
Chinese10 days
Egyptian Calendar10 daysThe 10-day period was known as decans or decades
French Republican Calendar10 days
Aztecs13 daysTrecena, division of the Tonalpohualli 260-day period

Calendaring and timekeeping standards

  • 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

  • Darian calendar (proposed for Mars, not used in planetary science)
  • Discworld calendar (fictional)
  • Middle-earth calendars (fictional)
  • Stardates (from Star Trek, fictional)

See also


  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. ^ "Tranquility Calendar, the".
  4. ^ Angelicus M. B. Onasanya, The Urgency of Now!: Building a True Nigerian Nation
  5. ^ Rhys (1840-1915), Sir John (1892). Lectures on the Origin and Growth of Religion as Illustrated by Celtic Heathendom. pp. 360–382.
  6. ^ Rhys, Sir John; Brynmor-Jones, David (1900). 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.
  • 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.