Buddhist calendar

The Buddhist calendar ( Pali: Sāsanā Sakaraj; Burmese: သာသနာ သက္ကရာဇ်, [θàðənà θɛʔkəɹɪʔ]; Khmer: ពុទ្ធសករាជ; Sinhala: බුද්ධ වර්‍ෂ or සාසන වර්‍ෂ (Buddha Varsha or Sāsana Varsha)) 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 for religious and/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.

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.

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.


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]

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]

BE Year Equivalent CE Years Equivalent CE Year (Thai Solar)
0 544–543 BCE
1 543–542 BCE
543 1 BCE – 1 CE
544 1–2 CE 1–2 CE
2483 1940–1941 1940 (Apr–Dec)
2484 1941–1942 1941
2556 2013–2014 2013



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.)

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]

Type Days Description
Waxing 1 to 15 from New Moon to Full Moon
Full Moon 15 Full Moon
Waning 1 to 14 or 15 from Full Moon to New Moon
New Moon 15 New Moon

Number of days per month

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

Sanskrit Pali Burmese Khmer Lao Sinhala Thai [9] # of days ~Gregorian
Caitra Citta Tagu (တန်ခူး) ចេត្រ ຈິຕ Bak (බක්) Chittra (จิตร) 29 March–April
Vaisākha Visakha Kason (ကဆုန်) ពិសាខ ວິສາຂະ Vesak (වෙසක්) Wisakha (วิสาข) 30 April–May
Jyaiṣṭha Jeṭṭha Nayon (နယုန်) ជេស្ឋ ເຊດ Poson (පොසොන්) Chettha (เชษฐ) 29 [30] May–June
Āṣāḍha Āsāḷha Waso (ဝါဆို) អាសាឍ ອາສາລະຫະ Æsala (ඇසළ) Asanha (อาสาฬห) 30 June–July
Śrāvaṇa Sāvaṇa Wagaung (ဝါခေါင်) ស្រាពណ៍ ສາວະນະ Nikini (නිකිණි) Sawana (สาวน) 29 July–August
Bhādrapada Poṭṭhapāda Tawthalin (တော်သလင်း) ភទ្របទ ພັດທະຣະບົດ Binara (බිනර) Phatthrabot (ภัทรบท) 30 August–September
Āśvina Assayuja Thadingyut (သီတင်းကျွတ်) អស្សុជ ອັດສະວະຍຸດ Wap (වප්) Atsawayut (อัศวยุช) 29 September–October
Kārttika Kattikā Tazaungmon (တန်ဆောင်မုန်း) កត្តិក ກັດຕິກາ Il (ඉල්) Kattika (กัตติกา) 30 October–November
Mārgaśirṣa Māgasira Nadaw (နတ်တော်) មិគសិរ ມິຄະສິນ Undhuvap (උඳුවප්) Mikkhasira (มิคสิร) 29 November–December
Pauṣa Phussa Pyatho (ပြာသို) បុស្ស ປຸສສ Dhuruthu (දුරුතු) Putsa (ปุสส) 30 December–January
Māgha Māgha Tabodwe (တပို့တွဲ) មាឃ ມາດ Navam (නවම්) Makha (มาฆ) 29 January–February
Phālguna Phagguṇa Tabaung (တပေါင်း) ផល្គុន ຜັກຄຸນ Mædhin (මැදින්) Phakkhun (ผัคคุณ) 30 February–March

Month numbering

Various regional versions of Chula Sakarat/Burmese calendar existed across various regions of mainland Southeast Asia. Unlike Cambodian and 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]

Month Lan Xang, Sukhothai, (and Old Burmese) Kengtung Chiang Mai
Caitra 5 6 7
Vaisakha 6 7 8
Jyestha 7 8 9
Ashadha 8 9 10
Sravana 9 10 11
Bhadrapada 10 11 12
Asvina 11 12 1
Karttika 12 1 2
Margasirsa 1 2 3
Pausa 2 3 4
Magha 3 4 5
Phalguna 4 5 6


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. [12] 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. [13]


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

Month Regular year Small leap year Big leap year
Tagu 29 29 29
Kason 30 30 30
Nayon 29 29 30
Waso 30 30 30
2nd Waso n/a 30 30
Wagaung 29 29 29
Tawthalin 30 30 30
Thadingyut 29 29 29
Tazaungmon 30 30 30
Nadaw 29 29 29
Pyatho 30 30 30
Tabodwe 29 29 29
Tabaung 30 30 30
Total 354 384 385

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

Cambodian, Lao and Thai

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]

Month Regular year Small leap year Big leap year
Caitra 29 29 29
Vaisakha 30 30 30
Jyestha 29 30 29
Ashadha 30 30 30
2nd Ashadha n/a n/a 30
Sravana 29 29 29
Bhadrapada 30 30 30
Asvina 29 29 29
Karttika 30 30 30
Margasirsa 29 29 29
Pausa 30 30 30
Magha 29 29 29
Phalguna 30 30 30
Total 354 355 384

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. [14] Thailand and Cambodia no longer use the traditional lunisolar calendar to mark the New Year's Day.

Tradition Date in 2013 Notes
Burmese 17 April Varies; will keep on drifting away
Thai 13 April Fixed to the solar calendar


Cambodian and Thai systems give animal names to the years from a cycle of 12. [15] The practice also existed in Burma in the Pagan period but later died out. [16]

Year Animal
1 Rat
2 Ox
3 Tiger
4 Rabbit
5 Dragon
6 Snake
7 Horse
8 Goat
9 Monkey
10 Rooster
11 Dog
12 Pig