Buddhist calendar

Last updated
Translations of
Buddhist calendar
Pali Sāsanā Sakaraj
Sanskrit बौद्ध पंचांग
Burmese သာသနာ သက္ကရာဇ်
(IPA:  [θàðənà θɛʔkəɹɪʔ] )
Khmer ពុទ្ធសករាជ
(UNGEGN: Puttheak-sakarach)
Sinhala බුද්ධ වර්‍ෂ / සාසන වර්‍ෂ
(Buddha Varsha / Sāsana Varsha)
Thai พุทธศักราช
(RTGS: phutthasakkarat)
Glossary of Buddhism

The Buddhist calendar is a set of lunisolar calendars primarily used in mainland Southeast Asian countries of Cambodia, Laos, Myanmar and Thailand as well as in Sri Lanka and Chinese populations of Malaysia and Singapore for religious or official occasions. While the calendars share a common lineage, they also have minor but important variations such as intercalation schedules, month names and numbering, use of cycles, etc. In Thailand, the name Buddhist Era is a year numbering system shared by the traditional Thai lunisolar calendar and by the Thai solar calendar.

A lunisolar calendar is a calendar in many cultures whose date indicates both the Moon phase and the time of the solar year. If the solar year is defined as a tropical year, then a lunisolar calendar will give an indication of the season; if it is taken as a sidereal year, then the calendar will predict the constellation near which the full moon may occur. As with all calendars which divide the year into months there is an additional requirement that the year have a whole number of months. In this case ordinary years consist of twelve months but every second or third year is an embolismic year, which adds a thirteenth intercalary, embolismic, or leap month.

Mainland Southeast Asia Peninsulas of Asia

Mainland Southeast Asia is the continental portion of Southeast Asia. It lies east of the Indian subcontinent and south of China and is bordered by the Indian Ocean to the west and the Pacific Ocean to the east. It includes the countries of Myanmar (Burma), Thailand, peninsular Malaysia, Laos, Cambodia and Vietnam.

Cambodia Southeast Asian sovereign state

Cambodia, officially the Kingdom of Cambodia, is a country located in the southern portion of the Indochina peninsula in Southeast Asia. It is 181,035 square kilometres in area, bordered by Thailand to the northwest, Laos to the northeast, Vietnam to the east and the Gulf of Thailand to the southwest.


The Southeast Asian lunisolar calendars are largely based on an older version of the Hindu calendar, which uses the sidereal year as the solar year. One major difference is that the Southeast Asian systems, unlike their Indian cousins, do not use apparent reckoning to stay in sync with the sidereal year. Instead, they employ their versions of the Metonic cycle. However, since the Metonic cycle is not very accurate for sidereal years, the Southeast Asian calendar is slowly drifting out of sync with the sidereal, approximately one day every 100 years. Yet no coordinated structural reforms of the lunisolar calendar have been undertaken.

Hindu calendar is a collective term for the various lunisolar calendars traditionally used in the Indian subcontinent. They adopt a similar underlying concept for timekeeping, but differ in their relative emphasis to moon cycle or the sun cycle and the names of months and when they consider the New Year to start. Of the various regional calendars, the most studied and known Hindu calendars are the Shalivahana Shaka found in South India, Vikram Samvat (Bikrami) found in North and Central regions of India, Tamil calendar used in Tamil Nadu, and the Bengali calendar used in the Bengal – all of which emphasize the lunar cycle. Their new year starts in spring. In contrast, in regions such as Kerala, the solar cycle is emphasized and this is called the Malayalam calendar, their new year starts in autumn, and these have origins in the second half of the 1st millennium CE. A Hindu calendar is sometimes referred to as Panchanga (पञ्चाङ्ग).

A sidereal year is the time taken by the Earth to orbit the Sun once with respect to the fixed stars. Hence, it is also the time taken for the Sun to return to the same position with respect to the fixed stars after apparently travelling once around the ecliptic. It equals 365.256 363 004 SI days for the J2000.0 epoch.

Metonic cycle period of very close to 19 years that is nearly a common multiple of the solar year and the synodic (lunar) month

For astronomy and calendar studies, the Metonic cycle or Enneadecaeteris is a period of very close to 19 years that is nearly a common multiple of the solar year and the synodic (lunar) month. The Greek astronomer Meton of Athens observed that a period of 19 years is almost exactly equal to 235 synodic months and, rounded to full days, counts 6,940 days. The difference between the two periods is only a few hours, depending on the definition of the year.

Today, the traditional Buddhist lunisolar calendar is used mainly for Theravada Buddhist festivals, and no longer has the official calendar status anywhere. The Thai Buddhist Era, a renumbered Gregorian calendar, is the official calendar in Thailand.

Theravada Branch of Buddhism

Theravāda is the most ancient branch of extant Buddhism today and the one that preserved their version of the teachings of Gautama Buddha in the Pāli Canon. The Pāli Canon is the only complete Buddhist canon which survives in a classical Indian language, Pāli, which serves as both sacred language and lingua franca of Theravāda Buddhism. For more than a millennium, Theravāda has focused on preserving the dhamma as preserved in its texts and it tends to be very conservative with regard to matters of doctrine and monastic discipline. Since the 19th century, meditation practice has been re-introduced and has become popular with a lay audience, both in traditional Theravada countries and in the west.

The Gregorian calendar is the calendar used in most of the world. It is named after Pope Gregory XIII, who introduced it in October 1582. The calendar spaces leap years to make the average year 365.2425 days long, approximating the 365.2422-day tropical year that is determined by the Earth's revolution around the Sun. The rule for leap years is:

Every year that is exactly divisible by four is a leap year, except for years that are exactly divisible by 100, but these centurial years are leap years if they are exactly divisible by 400. For example, the years 1700, 1800, and 1900 are not leap years, but the year 2000 is.


Thailand's version of the lunisolar Buddhist calendar August2004rs.png
Thailand's version of the lunisolar Buddhist calendar

The calculation methodology of the current versions of Southeast Asian Buddhist calendars is largely based on that of the Burmese calendar, which was in use in various Southeast Asian kingdoms down to the 19th century under the names of Chula Sakarat and Jolak Sakaraj. The Burmese calendar in turn was based on the "original" Surya Siddhanta system of ancient India (believed to be Ardharatrika school). [1] One key difference with Indian systems is that the Burmese system has followed a variation of the Metonic cycle. It is unclear from where, when or how the Metonic system was introduced; hypotheses range from China to Europe. [note 1] The Burmese system, and indeed the Southeast Asian systems, thus use a "strange" combination of sidereal years from Indian calendar in combination with the Metonic cycle better for tropical years. [2]

The Burmese calendar is a lunisolar calendar in which the months are based on lunar months and years are based on sidereal years. The calendar is largely based on an older version of the Hindu calendar, though unlike the Indian systems, it employs a version of the Metonic cycle. The calendar therefore has to reconcile the sidereal years of the Hindu calendar with the Metonic cycle's near tropical years by adding intercalary months and days at irregular intervals.

Chula Sakarat or Chulasakarat is a lunisolar calendar derived from the Burmese calendar, whose variants were in use by most mainland Southeast Asian kingdoms down to the late 19th century. The calendar is largely based on an older version of the Hindu calendar though unlike the Indian systems, it employs a version of the Metonic cycle. The calendar therefore has to reconcile the sidereal years of the Hindu calendar with Metonic cycle's tropical years by adding intercalary months and intercalary days on irregular intervals.

<i>Surya Siddhanta</i> an ancient Sanskrit text on astronomy

The Surya Siddhanta is the name of a Sanskrit treatise in Indian astronomy from the late 4th-century or early 5th-century CE. The text survives in several versions, was cited and extensively quoted in a 6th-century CE text by Varahamihira, was likely revised for several centuries under the same title. It has fourteen chapters. A 12th-century manuscript of the text was translated into English by Burgess in 1860.

Epochal date

In all Theravada traditions, the calendar's epochal year 0 date was the day in which the Buddha attained parinibbāna . However, not all traditions agree on when it actually took place. In Burmese Buddhist tradition, it was 13 May 544 BCE (Tuesday, Full moon of Kason 148 Anjanasakaraj). [3] But in Thailand, it was 11 March 545 BCE, the date which the current Thai lunisolar and solar calendars use as the epochal date. Yet, the Thai calendars for some reason have fixed the difference between their Buddhist Era (BE) numbering and the Christian/Common Era (CE) numbering at 543, [4] which points to an epochal year of 544 BCE, not 545 BCE. In Myanmar, the difference between BE and CE can be 543 or 544 for CE dates, and 544 or 543 for BCE dates, depending on the month of the Buddhist Era (as the Buddhist calendar straddles the Gregorian calendar—currently from April to April). In Sri Lanka, the difference between BE and CE is 544. [5]

Parinirvana in Buddhism, the final bliss of an enlightened being

In Buddhism, the term parinirvana is commonly used to refer to nirvana-after-death, which occurs upon the death of the body of someone who has attained nirvana during his or her lifetime. It implies a release from the Saṃsāra, karma and rebirth as well as the dissolution of the skandhas.

BE YearEquivalent
CE Years
Equivalent CE
(Thai Solar)
0544–543 BCE
1543–542 BCE
5431 BCE – 1 CE
5441–2 CE1–2 CE
24831940–19411940 (Apr–Dec)



The calendar recognizes two types of months: synodic month and sidereal month. [6] The Synodic months are used to compose the years while the 27 lunar sidereal days (Sanskrit: nakshatra ), alongside the 12 signs of the zodiac, are used for astrological calculations. [7] (The Burmese calendar also recognizes a solar month called Thuriya Matha, which is defined as 1/12th of a year. [8] But the solar month varies by the type of year such as tropical year, sidereal year, etc.)

Nakshatra is the term for lunar mansion in Hindu astrology and Indian Astronomy. A nakshatra is one of 28 sectors along the ecliptic. Their names are related to the most prominent asterisms in the respective sectors.

Waxing and waning

The days of the month are counted in two halves, waxing and waning. The 15th of the waxing is the civil full moon day. The civil new moon day is the last day of the month (14th or 15th waning). Because of the inaccuracy of the calendrical calculation systems, the mean and real (true) New Moons rarely coincide. The mean New Moon often precedes the real New Moon. [6] [7]

Waxing1 to 15from New Moon to Full Moon
Full Moon15Full Moon
Waning1 to 14 or 15from Full Moon to New Moon
New Moon15New Moon

Number of days per month, and translations into Asian languages:

As the Synodic lunar month is approximately 29.5 days, the calendar uses alternating months of 29 and 30 days. [6]

SanskritPaliBurmeseKhmerLaoSinhalaThai [9] No. of
Chaitra Citta Tagu (တန်ခူး)ចេត្រ
ຈິຕBak (බක්)Chittra (จิตร)29March–April
Vaisākha Visakha Kason (ကဆုန်)ពិសាខ
ວິສາຂະVesak (වෙසක්)Wisakha (วิสาข)30April–May
Jyaiṣṭha Jeṭṭha Nayon (နယုန်)ជេស្ឋ
ເຊດPoson (පොසොන්)Chettha (เชษฐ)29 [30]May–June
Āṣāḍha Āsāḷha Waso (ဝါဆို)អាសាឍ
ອາສາລະຫະÆsala (ඇසළ)Asanha (อาสาฬห)30June–July
Śrāvaṇa Sāvaṇa Wagaung (ဝါခေါင်)ស្រាពណ៍
ສາວະນະNikini (නිකිණි)Sawana (สาวน)29July–August
Bhādrapada or Proshthapada Poṭṭhapāda Tawthalin (တော်သလင်း)ភទ្របទ
ພັດທະຣະບົດBinara (බිනර)Phatthrabot (ภัทรบท)30August–September
Āśvina Assayuja Thadingyut (သီတင်းကျွတ်)អស្សុជ
ອັດສະວະຍຸດWap (වප්)Atsawayut (อัศวยุช)29September–October
Kārttika Kattikā Tazaungmon (တန်ဆောင်မုန်း)កត្តិក
ກັດຕິກາIl (ඉල්)Kattika (กัตติกา)30October–November
Mārgaśirṣa Māgasira Nadaw (နတ်တော်)មិគសិរ
ມິຄະສິນUndhuvap (උඳුවප්)Mikkhasira (มิคสิร)29November–December
Pauṣa Phussa Pyatho (ပြာသို)បុស្ស
ປຸສສDhuruthu (දුරුතු)Putsa (ปุสส)30December–January
Māgha Māgha Tabodwe (တပို့တွဲ)មាឃ
ມາດNavam (නවම්)Makha (มาฆ)29January–February
Phālguna Phagguṇa Tabaung (တပေါင်း)ផល្គុន
ຜັກຄຸນMædhin (මැදින්)Phakkhun (ผัคคุณ)30February–March

Month numbering and cultures:

Various regional versions of Chula Sakarat/Burmese calendar existed across various regions of mainland Southeast Asia. Unlike Burmese systems, Kengtung, Lan Na, Lan Xang and Sukhothai systems refer to the months by numbers, not by names. This means reading ancient texts and inscriptions in Thailand requires constant vigilance, not just in making sure one is correctly operating for the correct region, but also for variations within regions itself when incursions cause a variation in practice. [10] [11] However, Cambodian (Khmer) month system, which begins with Margasirsa as the first month, demonstrated precisely by the names and numbers. [12]

MonthKhmer, Lan Xang, Sukhothai and Old BurmeseKengtungChiang Mai


The Buddhist calendar is a lunisolar calendar in which the months are based on lunar months and years are based on solar years. One of its primary objectives is to synchronize the lunar part with the solar part. The lunar months, normally twelve of them, consist alternately of 29 days and 30 days, such that a normal lunar year will contain 354 days, as opposed to the solar year of ~365.25 days. Therefore, some form of addition to the lunar year (of intercalation) is necessary. The overall basis for it is provided by cycles of 57 years. Eleven extra days are inserted in every 57 years, and seven extra months of 30 days are inserted in every 19 years (21 months in 57 years). This provides 20819 complete days to both calendars. [13] This 57-year cycle would provide a mean year of about 365.2456 days and a mean month of about 29.530496 days, if not corrected.

As such, the calendar adds an intercalary month in leap years and sometimes also an intercalary day in great leap years. The intercalary month not only corrects the length of the year but also corrects the accumulating error of the month to extent of half a day. The average length of the month is further corrected by adding a day to Nayon at irregular intervals—a little more than seven times in two cycles (39 years). The intercalary day is never inserted except in a year which has an intercalary month. [7] The Hindu calendar inserts an intercalary month at any time of year as soon as the accumulated fractions amount to one month. The Burmese calendar however always inserts the intercalary month at the same time of the year, after the summer solstice while the Arakanese calendar inserts it after the vernal equinox. [14]

Burmese Calendar:

The actual Burmese calendar year consists of 354, 384 or 385 days.

MonthRegular yearSmall leap yearBig leap year
2nd Wason/a3030

Note: The Arakanese calendar adds the intercalary day in Tagu, not in Nayon.

Cambodian, Laotian and Thai Calendar:

The Cambodian, Lao and Thai lunar calendars use a slightly different method to place the intercalary day. Instead of it in a leap year as in the Burmese system, the Thai system places it in a separate year. Thus, the Thai small leap year has 355 days while the Thai great leap year has 384 days. [10]

MonthRegular yearSmall leap yearBig leap year
2nd Ashadhan/an/a30

New Year's Day

Since the main purpose of Buddhist calendar is to keep pace with the solar year, the new year is always marked by the solar year, which falls at the time when the Sun enters Aries. [6] The date, which at the present falls on the 17th of April, has slowly drifted over the centuries. In the 20th century, the New Year's Day fell on April 15 or 16th but in the 17th century, it fell on April 9 or 10th. [15] Thailand and Cambodia no longer use the traditional lunisolar calendar to mark the New Year's Day.

TraditionDate in 2013Notes
Burmese17 AprilVaries; will keep on drifting away
Khmer14 AprilVaries from 13th to 14th of April
Thai13 AprilFixed to the solar calendar

Zodiac Animal Cycle:

Animal year cycle system

Cambodian and Thai systems give animal names to the years from a cycle of 12. [16] The practice also existed in Burma in the Pagan period but later died out. [17]

YearAnimal Khmer Lao Thai
1 Rat ជូត (Choot)ຊວດ (Suat)ชวด (Chuat)
2 Ox ឆ្លូវ (Chhlov)ສະຫລູ (Salu)ฉลู (Chalu)
3 Tiger ខាល (Khal)ຂານ (Khan)ขาล (Khan)
4 Rabbit ថោះ (Thoh)ເຖາະ (Tho)เถาะ (Tho)
5 Naga រោង (Rorng)ມະໂລງ (Malong)มะโรง (Marong)
6 Snake ម្សាញ់ (Msanh)ມະເສງ (Maseng)มะเส็ง (Maseng)
7 Horse មមី (Momee)ມະເມັຽ (Mameh)มะเมีย (Mamia)
8 Goat មមែ (Momae)ມະແມ (Mamae)มะแม (Mamae)
9 Monkey វក (Vork)ວອກ (Wok)วอก (Wok)
10 Rooster រកា (Roka)ລະກາ (Laka)ระกา (Raka)
11 Dog ច (Char)ຈໍ (Cho)จอ (Cho)
12 Pig កុរ (Kol)ກຸນ (Kun)กุน (Kun)

Cambodian Zodiac Cycle:

In Cambodia, there is the sequence of year, which numbered from one to ten, used to identify a particular year, called "Sak" (Khmer: ស័ក) that means "era". It begins with a prefix "Aek, tor or trei", which means one, two or three respectively (using numerals that were derived from the Sanskrit language) then the suffix "Sak" is added to each prefix so as to form a word of the year. Cambodian use the Sak system to differentiate the twelve animal years that return every twelve year by including the ten-year system along with the animal year system. For instance, in 2017, the ten-year and animal year fall in the year of Rooster, Nuppasak (era 9), Buddhist Era of 2561 (based on Cambodian lunar calendar). [12]

NumbersNames in Khmer Transliteration


The Southeast Asian Buddhist calendars use lunar months but try to keep pace with the solar year, by inserting intercalary months and days on the Metonic cycle (in the case of the Burmese calendar, on a modified Metonic cycle). However, the solar year as defined by the Buddhist calendars is really a sidereal year, which is nearly 24 minutes longer than the actual mean tropical year. Therefore, like all sidereal-based calendars, the lunisolar calendars are slowly drifting away from the seasons. [18] The calendars are drifting one day approximately every 60 years and 4 months.

The accumulating drift against the seasons means the New Year's Day which used to fall on 22 March (near the vernal equinox) in 638 CE now falls on 17 April in 2013 CE. There is no known internationally concerted effort to stop this drift. Thailand has moved its "Buddhist Era" to the Gregorian calendar under the name of Thai solar calendar. In Myanmar, Burmese calendarists have tried to deal with the issue by periodically modifying the intercalation schedule in the Metonic cycle. One major downside of this approach is that it is not possible to publish future calendars more than a few years (often even a year) ahead. [note 2]


The Buddhist Era was first introduced to Southeast Asia along with Buddhism in the early centuries CE. It was not a separate calendar but simply a year numbering system that employed the organization and calculation methods of the prevailing lunisolar calendars in use throughout the region. In the early centuries CE, the reference civil calendar of the Buddhist calendar prevalent in Southeast Asia was the Saka Era (Mahāsakaraj Era), which is said to have been adopted by the Pyu state of Sri Ksetra in 80 CE. The Saka Era was gradually replaced by the Burmese Era or Culāsakaraj, first in Myanmar in 640 CE, [19] and in other Theravada kingdoms of Southeast Asia between the 13th and 16th centuries. [note 3] Theravada Buddhist tradition also recognizes pre-Buddhist Anjana Sakaraj (Añjana's Era) since the events of the Buddha's life are recorded in that era. [3]

NameEpochal dateNotes
Anjana Sakaraj10 March 691 BCESaid to have been started by the Buddha's maternal grandfather King Añjana
Used to date the events during the Buddha's lifetime
Buddhist Era13 May 544 BCE
11 March 545 BCE
544 BCE in Myanmar; 545 BCE in Thailand
Śaka Era 17 March 78 CECivil calendar
Burmese Era (Culāsakaraj)22 March 638Civil calendar

The tradition of using different reference calendars continued in Siam in 1912 when King Vajiravudh decreed that the Buddhist Era would now track the Thai solar calendar, the Siamese version of the Gregorian calendar with the New Year's Day of 1 April. Therefore, the Thai Buddhist Era year of 2455 began on 1 April 1912 (as opposed to 15 April 1912 according to the lunisolar calendar [20] ). The Thai Buddhist Era was further realigned to the Gregorian calendar on 6 September 1940 when Prime Minister Phibunsongkhram decreed 1 January 1941 as the start of the year 2484 BE. As a result, the Year 2483 was only 9 months long, and the Thai Buddhist Era equals that of the Common Era plus 543 years.

Current usage

The lunisolar calendar is used to mark important Buddhist holidays. Many of the holidays are celebrated as public holidays.

Buddhist calendar dateInternational datePublic holiday inNotes
Full moon of PausaJanuarySri LankaDuruthu Poya: Commemorates the first visit of the Buddha to Sri Lanka
Full moon of MaghaFebruaryCambodia, Laos, Sri Lanka, Thailand Magha Puja in Cambodia, Laos, Thailand and known as Navam Poya in Sri Lanka
Full moon of PhalgunaMarchLaos, Myanmar, Sri Lanka Boun Pha Vet (Laos), Tabaung Festival (Myanmar), Medin Poya (Sri Lanka)
Almost always in Caitra, sometimes in Vaisakha13–17 April
(varies by country)
Cambodia, Laos, Myanmar, Sri Lanka, Thailand Songkran (Southeast Asian New Year)
Traditionally, the New Year's Day is marked when the Sun enters Aries but the day is now fixed in most countries; Myanmar still follows the tradition. It also marks the beginning of the next Buddhist calendar animal zodiac year for certain countries.
Full moon of CaitraAprilSri LankaBak Poya: Commemorates the second visit of the Buddha to Sri Lanka
Full moon of VisakhaMayCambodia, Laos, Thailand, Sri Lanka, Myanmar, Malaysia, Singapore Buddha Day (Vesak)
Full moon of JyaisthaJuneSri LankaPoson Poya: Commemorates introduction of Buddhism to Sri Lanka
Full moon of AshadhaJulyCambodia, Laos, Myanmar, Thailand, Sri Lanka Vassa
Esala Poya (Sri Lanka)
Asalha Puja (Thailand)
Full moon of SravanaAugustSri LankaNikini Poya
Full moon of BhadrapadaSeptemberLaos, Sri LankaBinara Poya (Sri Lanka)
Full moon of AsvinaOctoberCambodia, Laos, Myanmar, Sri LankaEnd of Vassa
Boun Suang Huea (Laos); Thadingyut Festival (Myanmar); Vap Poya (Sri Lanka); Wan Ok Phansa (Thailand)
Full moon of KarttikaNovemberLaos, Myanmar, Sri Lanka, Thailand, Cambodia That Luang Festival (Laos); Tazaungdaing Festival (Myanmar); Il Poya (Sri Lanka); Loi Krathong (Thailand); Bon Om Touk (Cambodia)
Full moon of MargasirsaDecemberSri LankaUndhuvap Poya (Sri Lanka)

Computer Support

Since the release of Java 8, the Buddhist calendar is supported in the new Date and Time API. iOS has support to display Buddhist calendar years.

See also


  1. (Ohashi 2001: 398–399): Astronomers of ancient India certainly knew of the Metonic cycle, and may have introduced the concept to Southeast Asia. However, the Metonic cycle, which employs tropical years, is incompatible with sidereal based Hindu calendars, and thus was not (and still is not) used in Hindu calendars. Chatterjee (1998: 151) suggests that the Metonic system was introduced to Burma by Europeans. Ohashi (2001: 398–399) rejects Chatterjee's hypothesis saying that "no other trace of European influence is found in South-East Asian astronomy." Instead, Ohashi (2001: 401–403) suggests that China may have been the source of the Metonic cycle.
  2. (Irwin 1909: 26–27): In the mid-19th century, the Burmese Konbaung Dynasty tried to address the issue by introducing a new calculation methodology. However, the new solar year it chose was actually 0.56 second a year less accurate than the version still prevalent in the rest of Southeast Asia. The Konbaung court also modified the Metonic cycle, which did more to re-synchronize the calendar with the seasons than the less accurate solar year.
  3. (Eade 1989: 11): The earliest use of the Burmese calendar in lands part of present-day Thailand dates to the mid-13th century. (Smith 1966: 11): Ayutthaya adopted the Burmese calendar in the 16th century.

Related Research Articles

A calendar is a system of organizing days for social, religious, commercial or administrative purposes. This is done by giving names to periods of time, typically days, weeks, months and years. A date is the designation of a single, specific day within such a system. A calendar is also a physical record of such a system. A calendar can also mean a list of planned events, such as a court calendar or a partly or fully chronological list of documents, such as a calendar of wills.

Intercalation or embolism in timekeeping is the insertion of a leap day, week, or month into some calendar years to make the calendar follow the seasons or moon phases. Lunisolar calendars may require intercalations of both days and months.

Lunar calendar type of calendar

A lunar calendar is a calendar based upon the monthly cycles of the Moon's phases, in contrast to solar calendars, whose annual cycles are based only directly upon the solar year. The most commonly used calendar, the Gregorian calendar, is a solar calendar system that originally evolved out of a lunar calendar system. A purely lunar calendar is also distinguished from a lunisolar calendar, whose lunar months are brought into alignment with the solar year through some process of intercalation. The details of when months begin varies from calendar to calendar, with some using new, full, or crescent moons and others employing detailed calculations.

An epoch, for the purposes of chronology and periodization, 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.

A solar calendar is a calendar whose dates indicate the season or almost equivalently the apparent position of the Sun relative to the stars. The Gregorian calendar, widely accepted as standard in the world, is an example of a solar calendar. The main other type of calendar is a lunar calendar, whose months correspond to cycles of Moon phases. The months of the Gregorian calendar do not correspond to cycles of Moon phase.

The Thai lunar calendar, or Tai calendar, is a lunisolar Buddhist calendar. It is used for calculating lunar-regulated holy days. Based on the SuriyaYatra, with likely influence from the traditional Hindu Surya Siddhanta, it has its own unique structure that does not require the Surya Siddhanta to calculate. Lunisolar calendars combine lunar and solar calendars for a nominal year of 12 months. An extra day or an extra 30-day month is intercalated at irregular intervals.

Thai solar calendar

The Thai solar calendar was adopted by King Chulalongkorn in 1888 CE as the Siamese version of the Gregorian calendar, replacing the Thai lunar calendar as the legal calendar in Thailand. Years are now counted in the Buddhist Era (B.E.): พุทธศักราช, พ.ศ., which is 543 years ahead of the Gregorian calendar.

Lunar New Year is the beginning of a calendar year whose months are coordinated by the cycles of the moon. The relevant calendar may be a purely lunar calendar or a lunisolar calendar.

The history of calendars, means that people creating and using methods for keeping track of days and larger divisions of time, covers a practice with ancient roots.

Calendar reform or calendrical reform, is any significant revision of a calendar system. The term sometimes is used instead for a proposal to switch to a different calendar design.

Vikram Samvat ; Listen ) is the historical Hindu calendar from the Indian subcontinent and the official calendar of modern-day India and Nepal. It uses lunar months and solar sidereal years.

Thai calendar Wikipedia disambiguation page

In Thailand, two main calendar systems are used alongside each other: the Thai solar calendar, based on the Gregorian calendar, used for official and most day-to-day purposes, and the Thai lunar calendar, used for traditional events and Buddhist religious practices.

Nisan-years is an ancient calendar system used around Mesopotamia. Its area of usage covers Elam, Persia, Media, Syria and Israel/Judea. Its beginning was from prehistorical era. Ever since Mesopotamia had historical writings, even before the Old Babylonian Empire of Hammurabi, its calendar used the Nisan-years.

A Small Mahzor is a 19-year cycle in the lunisolar calendar system used by the Jewish people. It is similar to, but slightly different in usage with, the Greek Metonic cycle.

Mesha Sankranti

Mesha Sankranti refers to the first day of the solar cycle year, that is the solar New Year in the Hindu luni-solar calendar. The Hindu calendar also has a lunar new year, which is religiously more significant, and falls on different dates in the Amanta and Purinamanta systems prevalent across the Indian subcontinent. The solar cycle year is significant in Oriya,Punjabi ,Malayalam,Tamil and Bengali calendars.


  1. Ohashi 2007: 354–355
  2. Ohashi 2001: 398–399
  3. 1 2 Kala Vol. 1 2006: 38
  4. Eade 1995: 15-16
  5. "Vesak 2005 | Ceylon Sri Lanka Stamp SS".
  6. 1 2 3 4 Clancy 1906: 56–57
  7. 1 2 3 Irwin 1909: 8–9
  8. Irwin 1909: 5
  9. Busyakul, 2004: 476.
  10. 1 2 Eade 1989: 9–10
  11. Eade 1995: 28–29
  12. 1 2 "Khmer Calendar".
  13. Eade 1995: 15
  14. Irwin 1909: 2–3
  15. Eade 1989: 135–145, 165–175
  16. Eade 1995: 22
  17. Luce 1970: 330
  18. Irwin 1909: 26–27
  19. Hmannan Vol. 1 2003: 216
  20. Eade 1989: 166