Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...

follows UTC+07:00, which is 7 hours ahead of UTC. The local mean time in

Bangkok Bangkok, officially known in Thai language, Thai as Krung Thep Maha Nakhon and colloquially as Krung Thep, is the capital and most populous city of Thailand. The city occupies in the Chao Phraya River delta in central Thailand and has an estima ...

was originally UTC+06:42:04. Thailand used this local mean time until 1920, when it changed to Indochina Time, UTC+07:00; ICT is used all year round as Thailand does not observe

daylight saving time Daylight saving time (DST), also referred to as daylight savings time or simply daylight time (United States, Canada, and Australia), and summer time (United Kingdom, European Union, and others), is the practice of advancing clocks (typicall ...

. Thailand shares the same time zone with

Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...

Cambodia Cambodia (; also Kampuchea ; km, កម្ពុជា, UNGEGN: ), officially the Kingdom of Cambodia, is a country located in the southern portion of the Indochinese Peninsula in Southeast Asia, spanning an area of , bordered by Thailand t ...

Laos Laos (, ''Lāo'' )), officially the Lao People's Democratic Republic ( Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ, French: République démocratique populaire lao), is a socialist ...

Christmas Island Christmas Island, officially the Territory of Christmas Island, is an Australian external territory comprising the island of the same name. It is located in the Indian Ocean, around south of Java and Sumatra and around north-west of the ...

, and Western Indonesia.

History

* Prior to 1 January 1901, locations in

Siam Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Mainland Southeast Asia, Indochinese Peninsula, spanning , with a population of almost 70 mi ...

with an

astronomical observatory An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. His ...

would adopt

local mean time Local mean time (LMT) is a form of solar time that corrects the variations of Solar time#Apparent solar time, local apparent time, forming a uniform time scale at a specific longitude. This measurement of time was used for everyday use during the ...

based on the observatory's geographic position.

Chiang Mai Province Chiang Mai ( th, เชียงใหม่, ; nod, , ) is the largest Province (''changwat'') of Thailand. It lies in upper northern Thailand and has a population of 1.78 million people. It is bordered by Chiang Rai to the northeast, Lam ...

and two other provinces each had an observatory, hence, each province had its own distinct local mean time, with minutes of difference between the three locations. * On 1 April 1920, the mean time of the 105th meridian east (passing through Ubon Ratchathani Province) was adopted by

as the new

standard time Standard time is the synchronisation of clocks within a geographical region to a single time standard, rather than a local mean time standard. Generally, standard time agrees with the local mean time at some meridian that passes through the r ...

. The mean time of the 105th meridian is 7 hours ahead of

Greenwich Mean Time Greenwich Mean Time (GMT) is the Local mean time, mean solar time at the Royal Observatory, Greenwich, Royal Observatory in Greenwich, London, counted from midnight. At different times in the past, it has been calculated in different ways, i ...

(i.e., local mean time at the

Greenwich Royal Observatory The Royal Observatory, Greenwich (ROG; known as the Old Royal Observatory from 1957 to 1998, when the working Royal Greenwich Observatory, RGO, temporarily moved south from Greenwich to Herstmonceux) is an observatory situated on a hill in G ...

). * In July 2001, Thailand announced its intention of moving its time forward one hour, to align with both

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

and

Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...

and more importantly with

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

, Central Indonesia, and

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...

, i.e., UTC+08:00. This was met with much criticism and resistance and the plan was withdrawn.

Standardisation of time in Thailand

Thailand declared on 16 March 1920 that people would move their clocks ahead by 17 minutes, 56 seconds on 31 March 1920 to match the time in use in

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

. The time was switched on 1 April 1920 at 00:00 (old time) to 00:17:56 (new time).

Timekeeper

On 1 January 1990, the

Cabinet of Thailand The cabinet of Thailand or, formally, the Council of Ministers of Thailand ( th, คณะรัฐมนตรี; is a body composed of thirty-five of the most senior members of the government of the Kingdom of Thailand. The cabinet is the pri ...

appointed the

Royal Thai Navy The Royal Thai Navy ( Abrv: RTN, ทร.; th, กองทัพเรือไทย, ) is the naval warfare force of Thailand. Established in 1906, it was modernised by the Admiral Prince Abhakara Kiartiwongse (1880–1923) who is known as ...

as the official timekeeper for Thailand. Thai Standard Time is derived from five

atomic clock An atomic clock is a clock that measures time by monitoring the resonant frequency of atoms. It is based on atoms having different energy levels. Electron states in an atom are associated with different energy levels, and in transitions betwee ...

s maintained by the Royal Thai Navy.

References

External links

{{Asia topic, Time in

Time in Southeast Asia

History

Standardisation of time in Thailand

Timekeeper

See also

References

External links