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 itself, are in turn modifications 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 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
Vikram samwat	Lunisolar	Indian	Ancient India
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.
Four Seasons and Eight Nodes (四時曆)	solar	Chinese	Bronze Age(?)	China	The years is divided into four seasons, and each season is divided into a festival(四立) and three months. The start and middle of each season is the key node of the year.
Gezer Calendar	lunar	Mesopotamian	1000 BC	Israel/Canaan	The years are divided into monthly or bi-monthly periods and attributes to each a duty such as harvest, planting, or tending specific crops.
Roman calendar	lunisolar	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).
Nisg̱a'a	seasonal / lunisolar	Indigenous North America		Nisg̱a'a	The Nisga’a calendar revolves around harvesting of foods and goods used. The original year followed the various moons throughout the year.
Haida	lunar	Indigenous North America		Haida	The Haida calendar is a lunar calendar broken into two seasons (winter and summer) of six months each with an occasional thirteenth month between seasons.
Inuit	seasonal	Indigenous North America		Inuit	The 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 BC	Maya
Tzolk'in	fixed (260 days)	Pre-Columbian (Maya)	1st millennium BC	Maya
Xiuhpohualli	fixed (365 days)	Pre-Columbian (Aztec)		Aztecs
Tonalpohualli	fixed (260 days)	Pre-Columbian (Aztec)		Aztecs
Attic calendar	lunisolar (354/ 384 days)	Hellenic	6th century BC	Classical Athens	The 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 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.
Genesis Calendar (太初曆)	lunisolar	Chinese	Han dynasty	China	Introduced the "month without mid-climate is intercalary" rule; based on a solar year of 365³⁸⁵⁄₁₅₃₉ days and a lunar month of 29⁴³⁄₈₁ days (19 years=235 months=6939⁶¹⁄₈₁ 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	Coptic Orthodox Church	Based on both the Ptolemaic calendar and the Julian calendar
Ge'ez calendar	solar	Egyptian	1st century	Ethiopia, Ethiopian Christians, Eritrea, Eritrean Christians	the calendar associated with Ethiopian and Eritrean Churchs, based on the Coptic calendar
Berber calendar	solar	Julian	In Roman times	North Africa	Julian calendar used for agricultural work.
Qumran calendrical texts	fixed (364 days)	—	c. 1st century	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	Gauls/Celts (no longer in use)	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.
Chinese Calendar, Dàmíng origin (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
Chinese Calendar, Wùyín origin(戊寅元曆)	lunisolar	Chinese	619	China	First Chinese calendar to use the true moon motion
Islamic calendar	lunar	Muslim	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	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/ Hindu	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	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	Bulgarian	Bronze Age	Volga Bulgaria	A 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 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	Ancient	Tamil Nadu	The Hindu calendar used in Tamil Nadu
Nepali calendar	solar	Hindu/ Buddhist	medieval	Nepal	One of the Hindu calendars
Bengali calendar	lunisolar	Bengali	medieval	Bengal	Revised in 1987.
Thai lunar calendar	lunisolar	Hindu/Buddhist	medieval	Thailand	A Buddhist calendar
Pawukon calendar	fixed (210 days)	Hindu		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/Chinese-derived	13th century	Tibet	The Kalacakra, a Buddhist calendar introduced in 13th-century Tibet
Seasonal Instruction (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.
Six Imperial Calendars (ß)	solar	Chinese	Ming dynasty	China	In use 1368-1644
Incan calendar	lunisolar	Pre-Columbian	15th century	Inca Empire
Muisca calendar	lunisolar	Pre-Columbian	15th century	Muisca	Complex 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 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.
Seasonal Constitution (时宪历)	solar	Chinese	1645	China	First Chinese Calendar to use the true motion of the sun.
Swedish calendar	solar	Julian-derived	1700	Sweden	Part of the controversy surrounding the adoption of the Gregorian calendar, in use 1700–1712.
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.
Badí‘ calendar	solar	Baháʼí	1873	Baháʼí	Uses 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 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	Months and days use the Gregorian calendar, introduced in China in 1912.
Revised Julian calendar	solar	Julian-derived	1923	some Orthodox churches	currently 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 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.
Era Fascista	solar	Gregorian	1926	Italy	Epoch is 29 October 1922; in use from 1926–1943
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	—	Perpetual calendar with 1–2 off-week days, preferred and almost adopted by the United Nations in 1950s
Pax Calendar	solar	Gregorian	1930	—	Leap week calendar
Pataphysical calendar	solar	Gregorian	1949	—	Absurdist variant of the Gregorian calendar by Alfred Jarry.
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	—	Divides the year into four seasons.
Dreamspell	lunar/solar galactic	Mayan	1990	esotericism	13 months of 28 days each, synchronized with the Maya 260-day Tzolkin, calibrated to the Chilam Balam timing systems
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 with 4:5:4 weeks per month
Hanke-Henry Permanent Calendar	solar	Gregorian	2004	—	Leap week calendar with 30:30:31 days per month, revised in 2011 and 2016
Igbo calendar	lunar	Indigenous West African	2009	Igbo people	Proposal[3] 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

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
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.
Slavic calendar	Slavic	Local month names in various Slavic countries, based on weather patterns and conditions, and agricultural activities that take place in each respective month.
Romanian calendar	Romania	Traditional names for the twelve months of the Gregorian calendar, which are usually used by the Romanian Orthodox Church.

Non-standard weeks

Tradition	week length	comments
Bali	various
Korea	5 days
Java	5 days
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.[4][5]
Baltic	9 days	Linguistic reconstruction; the Gediminas Sceptre indicated that a week lasted for nine days during King Gediminas' reign.
Chinese	10 days
Egyptian Calendar	10 days	The 10-day period was known as decans or decades
French Republican Calendar	10 days
Aztecs	13 days	Trecena, 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)

References

Parker, Richard A., "The Calendars of Ancient Egypt", Studies in Ancient Oriental Civilization, 26. Chicago: University of Chicago Press, 1950.
Stern (2012) p. 179
Angelicus M. B. Onasanya, The Urgency of Now!: Building a True Nigerian Nation
Rhys (1840-1915), Sir John (1892). Lectures on the Origin and Growth of Religion as Illustrated by Celtic Heathendom. pp. 360–382.
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.

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[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] Angelicus M. B. Onasanya, The Urgency of Now!: Building a True Nigerian Nation

[4] Rhys (1840-1915), Sir John (1892). Lectures on the Origin and Growth of Religion as Illustrated by Celtic Heathendom. pp. 360–382.

[urlTheWelsh-5] 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.

List of calendars