Calendar era

Last updated

2024 in various calendars
Gregorian calendar 2024
Ab urbe condita 2777
Armenian calendar 1473
Assyrian calendar 6774
Baháʼí calendar 180–181
Balinese saka calendar 1945–1946
Bengali calendar 1431
Berber calendar 2974
British Regnal year 2  Cha. 3   3  Cha. 3
Buddhist calendar 2568
Burmese calendar 1386
Byzantine calendar 7532–7533
Chinese calendar 癸卯年 (Water  Rabbit)
4721 or 4514
甲辰年 (Wood  Dragon)
4722 or 4515
Coptic calendar 1740–1741
Discordian calendar 3190
Ethiopian calendar 2016–2017
Hebrew calendar 5784–5785
Hindu calendars
 - Vikram Samvat 2080–2081
 - Shaka Samvat 1945–1946
 - Kali Yuga 5124–5125
Holocene calendar 12024
Igbo calendar 1024–1025
Iranian calendar 1402–1403
Islamic calendar 1445–1446
Japanese calendar Reiwa 6
Javanese calendar 1957–1958
Juche calendar 113
Julian calendar Gregorian minus 13 days
Korean calendar 4357
Minguo calendar ROC 113
Nanakshahi calendar 556
Thai solar calendar 2567
Tibetan calendar 阴水兔年
(female Water-Rabbit)
2150 or 1769 or 997
(male Wood-Dragon)
2151 or 1770 or 998
Unix time 1704067200 – 1735689599

A calendar era is the period of time elapsed since one epoch of a calendar and, if it exists, before the next one. [1] For example, it is the year 2024 as per the Gregorian calendar, which numbers its years in the Western Christian era (the Coptic Orthodox and Ethiopian Orthodox churches have their own Christian eras).


In antiquity, regnal years were counted from the accession of a monarch. This makes the chronology of the ancient Near East very difficult to reconstruct, based on disparate and scattered king lists, such as the Sumerian King List and the Babylonian Canon of Kings. In East Asia, reckoning by era names chosen by ruling monarchs ceased in the 20th century except for Japan, where they are still used.

Ancient dating systems

Assyrian eponyms

For over a thousand years, ancient Assyria used a system of eponyms to identify each year. Each year at the Akitu festival (celebrating the Mesopotamian new year), one of a small group of high officials (including the king in later periods) would be chosen by lot to serve as the limmu for the year, which meant that he would preside over the Akitu festival and the year would bear his name. The earliest attested limmu eponyms are from the Assyrian trading colony at Karum Kanesh in Anatolia, dating to the very beginning of the 2nd millennium BC, [2] and they continued in use until the end of the Neo-Assyrian Period, c.612 BC.

Assyrian scribes compiled limmu lists, including an unbroken sequence of almost 250 eponyms from the early 1st millennium BC. This is an invaluable chronological aid, because a solar eclipse was recorded as having taken place in the limmu of Bur-Sagale, governor of Guzana. Astronomers have identified this eclipse as one that took place on 15 June 763 BC, which has allowed absolute dates of 892 to 648 BC to be assigned to that sequence of eponyms. [3] This list of absolute dates has allowed many of the events of the Neo-Assyrian Period to be dated to a specific year, avoiding the chronological debates that characterize earlier periods of Mesopotamian history.

Olympiad dating

Among the ancient Greek historians and scholars, a common method of indicating the passage of years was based on the Olympic Games, first held in 776 BC. The Olympic Games provided the various independent city-states with a mutually recognizable system of dates. Olympiad dating was not used in everyday life. This system was in use from the 3rd century BC. The modern Olympic Games (or Summer Olympic Games beginning 1896) do not continue the four year periods from ancient Greece: the 669th Olympiad would have begun in the summer of 1897, but the modern Olympics were first held in 1896. [4] :769

Indiction cycles

Another common system was the indiction cycle (15 indictions made up an agricultural tax cycle in Roman Egypt, an indiction being a year in duration). Documents and events began to be dated by the year of the cycle (e.g., "fifth indiction", "tenth indiction") in the 4th century, and this system was used long after the tax ceased to be collected. It was used in Gaul, in Egypt until the Islamic conquest, and in the Eastern Roman Empire until its conquest in 1453.

The rule for computing the indiction from the AD year number, which he had just invented, was stated by Dionysius Exiguus: add 3 and divide by 15; the remainder is the indiction, with 0 understood to be the fifteenth indiction. [4] :770 Thus the indiction of 2001 was 9. [5] The beginning of the year for the indiction varied. [4] :769–71

Seleucid era

The Seleucid era was used in much of the Middle East from the 4th century BC to the 6th century AD, and continued until the 10th century AD among Oriental Christians. The era is computed from the epoch 312 BC: in August of that year Seleucus I Nicator captured Babylon and began his reign over the Asian portions of Alexander the Great's empire. Thus depending on whether the calendar year is taken as starting on 1 Tishri or on 1 Nisan (respectively the start of the Jewish civil and ecclesiastical years) the Seleucid era begins either in 311 BC (the Jewish reckoning) or in 312 BC (the Greek reckoning: October–September).

Ancient Rome

Consular dating

An early and common practice was Roman 'consular' dating. This involved naming both consules ordinarii who had taken up this office on 1 January (since 153 BC) of the relevant civil year. [4] :6 Sometimes one or both consuls might not be appointed until November or December of the previous year, and news of the appointment may not have reached parts of the Roman empire for several months into the current year; thus we find the occasional inscription where the year is defined as "after the consulate" of a pair of consuls.

The use of consular dating ended in AD 541 when the emperor Justinian I discontinued appointing consuls. The last consul nominated was Anicius Faustus Albinus Basilius. Soon afterwards, imperial regnal dating was adopted in its place.

Dating from the founding of Rome

Another method of dating was ab urbe condita (Latin for "from the founding of the city" of Rome) or anno urbis conditae (Latin for "in the year of the founding of the city"), both abbreviated AUC.

Several epochs for this date were in use by Roman historians, all based on the incomplete surviving list of Roman consuls and the myths of the city's founding by Romulus and Remus. The chronology established by Marcus Terentius Varro in the 1st century BC intercalated several years of dictatorships, a period of anarchy, and a standardized length of reign for all of Rome's former kings to arrive at a year running from 754753 BC, [6] taken as equivalent to the 3rd year of the 6th Olympiad. Because the Parilia had become associated with the founding of the city by his time, he took the specific date to have been 21 April 753 BC. This became the official chronology of the empire by at least the time of Claudius, who held Secular Games in AD 47 to celebrate the city's 800th anniversary. The 900th and 1000th anniversaries were then celebrated in 148 under Antoninus Pius and in 248 under Philip I.

The AUC era was seldom used in the traditional Roman or early Julian calendars. Naming each year by its two consuls or by the emperor's regnal years predominated, with Hadrian's aurei [7] and sestertii marking the Romaea in AUC 874 (ann dccclxxiiii nat vrb) a notable exception. [8] AUC dating became more common in late antiquity, appearing in Censorinus, Orosius, and others. During the early Middle Ages, some church officials like Boniface IV employed AUC and AD dating together.[ citation needed ]

Historical Roman dating employed several different dates for the beginning of the year. Modern application of the AUC era generally ignores this, the known mistakes [6] in Varro's own calculations, and the 752 BC epoch used by the Fasti and later Secular Games, such that AD 2024 is generally considered equivalent to AUC 2777 (2024 + 753).

Regnal years of Roman emperors

Another system that is less commonly found than might be thought was the use of the regnal year of the Roman emperor. At first, Augustus indicated the year of his reign by counting how many times he had held the office of consul, and how many times the Roman Senate had granted him the power of a tribune (Latin : tribunicia potestas, abbr. TRP), carefully observing the fiction that his powers came from these offices granted to him, rather than from his own person or the many legions under his control. His successors followed his practice until the memory of the Roman Republic faded (about AD 200), when they began to use their regnal year openly.

Dating from the Roman conquest

Some regions of the Roman Empire dated their calendars from the date of Roman conquest, or the establishment of Roman rule.

The Spanish era counted the years from 38 BC, probably the date of a new tax imposed by the Roman Republic on the subdued population of Iberia. The date marked the establishment of Roman rule in Spain and was used in official documents in Portugal, Aragon, Valencia, and in Castile, into the 14th century. This system of calibrating years fell to disuse in 1381 and was replaced by today's Anno Domini. [9]

Throughout the Roman and Byzantine periods, the Decapolis and other Hellenized cities of Syria and Palestine used the Pompeian era, counting dates from the Roman general Pompey's conquest of the region in 63 BC.


A different form of calendar was used to track longer periods of time, and for the inscription of calendar dates (i.e., identifying when one event occurred in relation to others). This form, known as the Long Count, is based upon the number of elapsed days since a mythological starting-point. According to the calibration between the Long Count and Western calendars accepted by the great majority of Maya researchers (known as the GMT correlation), this starting-point is equivalent to 11 August, 3114 BC in the proleptic Gregorian calendar or 6 September in the Julian calendar (−3113 astronomical).

Other dating systems

A great many local systems or eras were also important, for example the year from the foundation of one particular city, the regnal year of the neighboring Persian emperor, and eventually even the year of the reigning Caliph.

Late Antiquity and Middle Ages

Most of the traditional calendar eras in use today were introduced at the time of transition from Late Antiquity to the Early Middle Ages, roughly between the 6th and 10th centuries.

Christian era

Dionysian "Common Era"

The era based on the Incarnation of Christ was introduced by Dionysius Exiguus in 525 and is in continued use with various reforms and derivations. The distinction between the Incarnation being the conception or the Nativity of Jesus was not drawn until the late ninth century. [4] :881 The beginning of the numbered year varied from place to place: when, in 1600, Scotland adopted 1 January as the date the year number changes, this was already the case in much of continental Europe. England adopted this practice in 1752. [4] :7

  • A.D. (or AD) – for the Latin Anno Domini , meaning "in the year of (our) Lord". This is the dominant or Western Christian Era; AD is used in the Gregorian calendar. Anno Salutis , meaning "in the year of salvation" is identical. Originally intended to number years from the Incarnation of Jesus, according to modern thinking the calculation was a few years off. Years preceding AD 1 are numbered using the BC era, avoiding zero or negative numbers. AD was also used in the medieval Julian calendar, but the first day of the year was either 1 March, Easter, 25 March, 1 September, or 25 December, not 1 January. To distinguish between the Julian and Gregorian calendars, O.S. and N.S. were often added to the date, especially during the 17th and 18th centuries, when both calendars were in common use. Old Style (O.S.) was used for the Julian calendar and for years not beginning on 1 January. New Style (N.S.) was used for the Gregorian calendar and for Julian calendar years beginning on 1 January. Many countries switched to using 1 January as the start of the numbered year at the same time as they switched from the Julian calendar to the Gregorian calendar, but others switched earlier or later.
  • B.C. (or BC) – meaning "Before Christ". Used for years before AD 1, counting backwards so the year n BC is n years before AD 1. Thus there is no year 0.
  • C.E. (or CE) and B.C.E. (or BCE) – meaning "Common Era" and "Before the Common Era", numerically equivalent to AD and BC, respectively (in writing, "AD" precedes the year number, but "CE" follows the year: AD 1 = 1 CE.) [10] The Latin equivalent vulgaris aera was used as early as 1615 by Johannes Kepler. [11] The English abbreviations C.E. and B.C.E. were introduced in the 19th century by Jewish intellectuals, wishing to avoid the abbreviation for dominus "lord" in implicit reference to Christ. [12] By the later 20th century, the abbreviations had come into wider usage by authors who wished to emphasize secularism. [13]



Southeast Asia

The Hindu Saka Era influences the calendars of southeast Asian indianized kingdoms.

B.E. of the Bahá'í calendar is below.








See also

Related Research Articles

<i>Anno Domini</i> Western calendar era

The terms anno Domini (AD) and before Christ (BC) are used when designating years in the Julian and Gregorian calendars. The term anno Domini is Medieval Latin and means "in the year of the Lord" but is often presented using "our Lord" instead of "the Lord", taken from the full original phrase "anno Domini nostri Jesu Christi", which translates to "in the year of our Lord Jesus Christ". The form "BC" is specific to English, and equivalent abbreviations are used in other languages: the Latin form, rarely used in English, is Ante Christum natum (ACN) or Ante Christum (AC).

<i>Ab urbe condita</i> Ancient Roman calendar era

Ab urbe condita, or anno urbis conditae, abbreviated as AUC or AVC, expresses a date in years since 753 BC, the traditional founding of Rome. It is an expression used in antiquity and by classical historians to refer to a given year in Ancient Rome. In reference to the traditional year of the foundation of Rome, the year 1 BC would be written AUC 753, whereas AD 1 would be AUC 754. The foundation of the Roman Empire in 27 BC would be AUC 727. The current year AD 2023 would be AUC 2776.

Common Era (CE) and Before the Common Era (BCE) are year notations for the Gregorian calendar, the world's most widely used calendar era. Common Era and Before the Common Era are alternatives to the original Anno Domini (AD) and Before Christ (BC) notations used for the same calendar era. The two notation systems are numerically equivalent: "2024 CE" and "AD 2024" each describe the current year; "400 BCE" and "400 BC" are the same year.

An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy, a calendar era used for a given calendar, or the geological eras defined for the history of Earth.

The Julian calendar is a solar calendar of 365 days in every year with an additional leap day every fourth year. The Julian calendar is still used in parts of the Eastern Orthodox Church and in parts of Oriental Orthodoxy as well as by the Amazigh people, whereas the Gregorian calendar is used in most parts of the world. It is named after Julius Caesar.

<span class="mw-page-title-main">Roman calendar</span> Calendar used by the Roman Kingdom and Roman Republic

The Roman calendar was the calendar used by the Roman Kingdom and Roman Republic. Although the term is primarily used for Rome's pre-Julian calendars, it is often used inclusively of the Julian calendar established by the reforms of the Dictator Julius Caesar and Emperor Augustus in the late 1st century BC.

AD 1 or 1 CE(I) is the epoch year for the Anno Domini (AD) Christian calendar era, and the 1st year of the 1st century and 1st millennium of the Christian and Common Era (CE). It was a common year starting on Saturday or Sunday, a common year starting on Saturday by the proleptic Julian calendar, and a common year starting on Monday by the proleptic Gregorian calendar.

The proleptic Julian calendar is produced by extending the Julian calendar backwards to dates preceding AD 8 when the quadrennial leap year stabilized. The leap years that were actually observed between the implementation of the Julian calendar in 45 BC and AD 8 were erratic.

The Julian day is the continuous count of days since the beginning of the Julian period, and is used primarily by astronomers, and in software for easily calculating elapsed days between two events.

In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured.

<span class="mw-page-title-main">Coptic calendar</span> Egyptian liturgical calendar

The Coptic calendar, also called the Alexandrian calendar, is a liturgical calendar used by the Coptic Orthodox Church and also used by the farming populace in Egypt. It was used for fiscal purposes in Egypt until the adoption of the Gregorian calendar on 11 September 1875. This calendar is based on the ancient Egyptian calendar. To avoid the calendar creep of the latter, a reform of the ancient Egyptian calendar was introduced at the time of Ptolemy III which consisted of adding an extra day every fourth year. However, this reform was opposed by the Egyptian priests, and the reform was not adopted until 25 BC, when the Roman Emperor Augustus imposed the Decree upon Egypt as its official calendar. To distinguish it from the Ancient Egyptian calendar, which remained in use by some astronomers until medieval times, this reformed calendar is known as the Coptic or Alexandrian calendar. Its years and months coincide with those of the Ethiopian calendar but have different numbers and names.

<span class="mw-page-title-main">Dionysius Exiguus</span> Byzantine saint (c. 470 – c. 544)

Dionysius Exiguus was a 6th-century Eastern Roman monk born in Scythia Minor. He was a member of a community of Scythian monks concentrated in Tomis, the major city of Scythia Minor. Dionysius is best known as the inventor of Anno Domini (AD) dating, which is used to number the years of both the Gregorian calendar and the (Christianised) Julian calendar. Almost all churches adopted his computus for the dates of Easter.

Annianus of Alexandria was a monk and writer who flourished in Alexandria during the pontificate of Theophilus I around the beginning of the 5th century.

The Ethiopian calendar, or Ge'ez calendar is the official calendar of Ethiopia. It is used as both the civil calendar and an ecclesiastical calendar. It is the liturgical year for Ethiopian and Eritrean Christians belonging to the Orthodox Tewahedo Churches, Eastern Catholic Churches, and Eastern Protestant Christian P'ent'ay Churches. The Ethiopian calendar is a solar calendar that has much in common with the Coptic calendar of the Coptic Orthodox Church of Alexandria and Coptic Catholic Church, but like the Julian calendar, it adds a leap day every four years without exception, and begins the year on 29 or 30 August in the Julian calendar. A gap of seven to eight years between the Ethiopian and Gregorian calendars results from an alternative calculation in determining the date of the Annunciation.

The Era of the Martyrs, also known as the Diocletian era, is a method of numbering years based on the reign of Roman Emperor Diocletian who instigated the last major persecution against Christians in the Empire. It was used by the Church of Alexandria beginning in the 4th century AD and it has been used by the Coptic Orthodox Church of Alexandria from the 5th century until the present. This era was used to number the year in Easter tables produced by the Church of Alexandria.

<i>Anno Mundi</i> Calendar era based on the biblical account of creation

Anno Mundi, abbreviated as AM or A.M., or Year After Creation, is a calendar era based on the biblical accounts of the creation of the world and subsequent history. Two such calendar eras have seen notable use historically:

A regnal year is a year of the reign of a sovereign, from the Latin regnum meaning kingdom, rule. Regnal years considered the date as an ordinal, not a cardinal number. For example, a monarch could have a first year of rule, a second year of rule, a third year of rule, and so on, but not a zeroth year of rule.

The Holocene calendar, also known as the Holocene Era or Human Era (HE), is a year numbering system that adds exactly 10,000 years to the currently dominant numbering scheme, placing its first year near the beginning of the Holocene geological epoch and the Neolithic Revolution, when humans shifted from a hunter-gatherer lifestyle to agriculture and fixed settlements. The current year by the Gregorian calendar, AD 2024, is 12024 HE in the Holocene calendar. The HE scheme was first proposed by Cesare Emiliani in 1993, though similar proposals to start a new calendar at the same date had been put forward decades earlier.

A year zero does not exist in the Anno Domini (AD) calendar year system commonly used to number years in the Gregorian calendar ; in this system, the year 1 BC is followed directly by year AD 1. However, there is a year zero in both the astronomical year numbering system, and the ISO 8601:2004 system, the interchange standard for all calendar numbering systems. There is also a year zero in most Buddhist and Hindu calendars.

<span class="mw-page-title-main">Byzantine calendar</span> Orthodox calendar used c. 691–1728

The Byzantine calendar, also called the Roman calendar, the Creation Era of Constantinople or the Era of the World, was the calendar used by the Eastern Orthodox Church from c. 691 to 1728 in the Ecumenical Patriarchate. It was also the official calendar of the Byzantine Empire from 988 to 1453 and of Kievan Rus' and Russia from c. 988 to 1700. This calendar was used also in other areas of the Byzantine commonwealth such as in Serbia, where it is found in old Serbian legal documents such as Dušan's Code, thus being referred to as the Serbian Calendar as well.


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  3. Millard, Alan (1994). The Eponyms of the Assyrian Empire, 910-612 BC (State Archives of Assyria Studies, Vol. 2). Helsinki: Neo-Assyrian Text Corpus Project. ISBN   978-9514567155.
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  5. Nautical Almanac Office of the United States Naval Observatory and Her Majesty's Nautical Almanac Office (2000). The Nautical Almanac for the year 2001. Washington, DC: Government Printing Office. p. B2.
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  8. Raddato, Carole (21 April 2021), "21 April AD 121 — Hadrian Celebrates Rome's 874th Birthday with Circus Games", Following Hadrian, Frankfurt {{citation}}: CS1 maint: location missing publisher (link).
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  11. A 1635 English edition of that book has the title page in English – so far, the earliest-found usage of "Vulgar Era" in English. The English phrase "common Era" appears at least as early as 1708.[ citation needed ] In Latin, "Common Era" is written as Vulgaris Aera. It also occasionally appears as æra vulgaris, aera vulgaris, anni vulgaris, vulgaris aera Christiana, and anni vulgatae nostrae aerae Christianas.
  12. Use of "C.E." and "B.C.E.": Morris Jacob Raphall. Post-Biblical History of The Jews (1856). Explicit use of "b.c.e." for "before the common era": Max Stern, Lemaʼan Yilmedu: A Second Hebrew Reader for Jewish Schools and Private Instruction (1881), p. 37.
  13. Sumser, John (2016). The Conflict Between Secular and Religious Narratives in the United States: Wittgenstein, Social Construction, and Communication. p. 69. ISBN   9781498522090. Archived from the original on 18 January 2021. Retrieved 2 October 2020.
  14. Cesare, E. (1993). Correspondence. Nature. 336: 716.{{cite journal}}: Missing or empty |title= (help)
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