Thai solar calendar

The Thai solar calendar (Thai: ปฏิทินสุริยคติ, RTGS: patithin suriyakhati, "solar calendar") was adopted by King Chulalongkorn (Rama V) in 1888 CE as the Siamese version of the Gregorian calendar, replacing the Thai lunar calendar as the legal calendar in Thailand (though the latter is still also used, especially for traditional and religious events). Years are now counted in the Buddhist Era (B.E.): พุทธศักราช, พ.ศ., (RTGS: Phutthasakkarat) which is 543 years ahead of the Gregorian calendar.

A panel from a typical calendar, showing the month of August 2004 (B.E. 2547). Note that lunar dates are also provided.


The Siamese generally used two calendars, a sacred and a popular (vulgar in the classical sense). The vulgar or minor era (จุลศักราช, chula sakarat) was thought to have been instituted when the worship of Gautama was first introduced,[1][2] and corresponds to the traditional Burmese calendar (abbreviated ME or BE, the latter not to be confused with the abbreviation for the Buddhist Era, which is the sacred era.)

Rattanakosin Era

King Chulalongkorn decreed a change in vulgar reckoning to the Rattanakosin Era (รัตนโกสินทรศก, Rattanakosin Sok abbreviated ร.ศ. and R.S.) in 1889 CE. The epoch (reference date) for Year 1 was 6 April 1782 with the accession of Rama I, the foundation of the Chakri dynasty, and the founding of Bangkok (Rattanakosin) as capital. To convert years in R.S. to the Common Era, add 1781 for dates from 6 April to December, and 1782 for dates from January to 5 April.

Buddhist Era

In Thailand the sacred, or Buddhist Era, is reckoned to have an epochal year 0 from 11 March 543 BC, believed to be the date of the death of Gautama Buddha. King Vajiravudh (Rama VI) changed year counting to this Buddhist Era (abbreviated BE) and moved the start of the year back to 1 April in 2455 BE, 1912 CE. As there is no longer any reference to a vulgar or popular era, the Common Era may be presumed to have taken the place of the former.

New year

New Year, the time at which a new calendar year begins and the calendar's year count is incremented, originally coincided with the date calculated for Songkran, when the Sun transits the constellation of Aries, the first astrological sign in the Zodiac as reckoned by sidereal astrology: thus the year commenced on 11 April 1822.[1] As previously noted, Rama VI moved the start of the year back to 1 April in 2455 BE, 1912 CE, so that 130 R.S. only lasted for 356 days from 11 April 1911 to 31 March 1912.

On 6 September 1940, Prime Minister Phibunsongkhram decreed[3] 1 January 1941 as the start of the year 2484 BE, so year 2483 BE had only nine months running from 1 April to 31 December 1940. To convert dates from 1 January to 31 March prior to that year, the number to add or subtract is 542; otherwise, it is 543. Example:

Month 1–34–67–910–12 1–34–67–910–12 1–34–67–910–12 1–34–67–910–12
CE 1939 1940 1941 1942
BE 2481 2482 2483 2484 2485
Thai Month 10–121–34–67–9 10–121–34–67–9 1–34–67–910–12 1–34–67–910–12

Today, both the Common Era New Year's Day (1 January) and the traditional Thai New Year (สงกรานต์, Songkran) celebrations (13–15 April) are public holidays in Thailand. In the traditional Thai calendar, the change to the next Chinese zodiacal animal occurs at Songkran (now fixed at 13 April.)[4] For Thai Chinese communities in Thailand, however, the Chinese calendar determines the day that a Chinese New Year begins, and assumes the name of the next animal in the twelve-year animal cycle.

Names of the months derive from Hindu astrology names for the signs of the zodiac. Thirty-day-month names end in -ayon (-ายน), from Sanskrit root āyana : the arrival of; 31-day-month names end in -akhom (-าคม), from Sanskrit āgama (cognate to English "come") that also means the arrival of.

February's name ends in -phan (-พันธ์), from Sanskrit bandha : "fettered" or "bound". The day added to February in a solar leap year is Athikasuratin (อธิกสุรทิน, respelled to aid pronunciation (อะทิกะสุระทิน) from Sanskrit adhika : additional; sura : move).[5]

English nameThai nameAbbr.Thai PronunciationSanskrit wordZodiac sign
Januaryมกราคมม.ค.mákàraa-khom, mókkàraa-khommakara "sea-monster"Capricorn
Februaryกุมภาพันธ์ก.พ.kumphaa-phankumbha "pitcher, water-pot"Aquarius
Marchมีนาคมมี.ค.miinaa-khommīna "fish"Pisces
Aprilเมษายนเม.ย.meesaǎ-yonmeṣa "ram"Aries
Mayพฤษภาคมพ.ค.phrɯ́tsaphaa-khomvṛṣabha "bull"Taurus
Juneมิถุนายนมิ.ย.míthùnaa-yonmithuna "a pair"Gemini
Julyกรกฎาคมก.ค.kàrákàdaa-khomkarkaṭa "crab"Cancer
Augustสิงหาคมส.ค.sǐnghǎa-khomsinha "lion"Leo
Septemberกันยายนก.ย.kanyaa-yonkanyā "girl"Virgo
Octoberตุลาคมต.ค.tùlaa-khomtulā "balance"Libra
Novemberพฤศจิกายนพ.ย.phrɯ́tsacìkaa-yonvṛścika "scorpion"Scorpio
Decemberธันวาคมธ.ค.thanwaa-khomdhanu "bow, arc"Sagittarius


DayColor of the day[6][7]Celestial BodyGod of the day
MondayYellow or CreamMoonChandra
Wednesday (Day)GreenMercuryBudha
Wednesday (Night)GreyRahu
ThursdayOrange or BrownJupiterBrihaspati
FridayLight BlueVenusShukra
SaturdayPurple or BlackSaturnShani


Using Buddhist era could easily cause confusion between itself and Anno Domini in the historical context. For example, Anno Domini 2023, and Buddhist year 2023 (which corresponds to 1479). Two-digit year numbering could cause even more confusion.

Another problem is the counting of the Buddhist era, which has changed several times in the past, including the inclusion of year 0, and the change of new year's day from April to January in 1941, has caused confusion in historical context as well. For example, many Thai people regard the establishment of the Ayutthaya Kingdom to be in 1350, which is direct conversion from Buddhist era 1893, while the actual date is 1351.

In computer programming, using the Buddhist era has sometimes caused the computer programs to void the license immediately, as the input values of the Buddhist era would exceed the expiration date for the program. Some users report that dates appear in future dates, due to the input data being the Buddhist era, while the computer is designed to accept Anno Domini.

See also


  1. Crawfurd, John (21 August 2006) [1830]. "Chapter I". Journal of an Embassy from the Governor-general of India to the Courts of Siam and Cochin China. Vol. 2 (2nd ed.). London: H. Colburn and R. Bentley. p. 32. OCLC 3452414. The Siamese year does not commence with the first month, but corresponds with that of the Chinese. In the year 1822, the new year fell on 11 April, being the 5th day of the dark half of the moon.... The Siamese have two epochs, or, as they describe them, Sa-ka-rat. The sacred one dates from the death of Gautama, and the year which commenced on 11 April 1822, was the year 2365, according to this reckoning.
  2. Roberts, Edmund (2007) [1837]. "Chapter XX―Division of Time". Embassy to the Eastern courts of Cochin-China, Siam, and Muscat : in the U. S. sloop-of-war Peacock ... during the years 1832-3-4 (Digital ed.). Harper & brothers. p. 310. ISBN 9780608404066. The Siamese have two epochs, sacred and popular. The sacred era dates from the death of Gautama, and the year 1833 corresponded to the 2376 year. The vulgar era was instituted when the worship of Gautama was first introduced; and the year 1833 corresponded with the year 1194, and was the fifth, or Dragon year.
  3. พระราชบัญญัติปีปฏิทิน พุทธศักราช ๒๔๘๓ (PDF). Royal Gazette (in Thai). 57 (ก): 419. 17 September 1940.
  4. J.C. Eade. The calendrical systems of mainland southeast asia. E.J. Brill, Leiden. p. 22. ISBN 90-04-10437-2. According to some scholars including George Coedes the change occurred at the beginning of the 5th lunar month originally a few days before Songkhran.
  5. Archived 28 September 2007 at the Wayback Machine, dictionary
  6. Segaller, Denis (2005). Thai Ways. Bangkok: Silkworm Books. ISBN 9781628400083.
  7. "Travel in numbers and colours: Wear pink for luck on Tuesdays in". The Independent. 2 June 2015. Retrieved 20 May 2017.


  • Eade, John Christopher. 1995. The Calendrical Systems of Mainland South-East Asia. Handbuch der Orientalistik: Dritte Abteilung, Südostasien 9. Leiden and New York: E. J. Brill. ISBN 90-04-10437-2
  • na Nakorn, Bleung (comp.). [1971]. นายเปลื้อง ณ นคร ผู้รวบรวม ปทานุกรมนักเรียน ไทยวัฒนาพานิช กทม. Student's Handbook. Bangkok: Thai Wattana Panit, 2514.
  • Sethaputra, So. 1999. New Model English – Thai Dictionary. [Krung Thep Maha Nakhon?: Thai Watthana Phanit?]. ISBN 974-08-3253-9
  • Thai calendar for August 2004.
  • Web dictionary Thai-English English-Thai
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