Time in Thailand

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Thailand follows UTC+7, which is 7 hours ahead of Greenwich Mean Time and Coordinated Universal Time. The local mean time in Bangkok was originally GMT+06:42:04.[1] Thailand used this local mean time until 1920, when they changed to Indochina Time GMT+07:00.


  • Prior to 1 January 1901 - locations in Siam with an Astronomical Observatory would adopt the local mean time based on the Observatory's geographical position. Phayap and Ratchaburi all had their own observatories; hence, the three provinces had their respective Local Mean Time, with minutes of differences amongst the three locations.
Period in use Time offset from GMT Name of Time (unofficial)
1 January 1880 - 31 March 1920 UTC+6:42:04 Bangkok Mean Time
1 April 1920 – present UTC+7 Indochina time

Standardisation of time in Thailand[edit]

Thailand declared that people would move their clocks ahead by 17-minutes 56-seconds to match the time in use in Southeast Asia (UTC+06:42:04 hrs and UTC+07:00:00 ahead of Greenwich Mean Time) on 31 March 1920. The time was switched on 1 April 1920 at 06:00 (old time) to 06:17:56 (new time).


On 1 January 1990, the Thai Cabinet appointed the Royal Thai Navy as the official timekeeper for Thailand. Thai Standard Time is derived from 5 atomic clocks maintained by the Royal Thai Navy.

See also[edit]


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