Time in Thailand
follows UTC+07:00, which is 7 hours ahead of UTC. The local mean time in Bangkok 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. Thailand shares the same time zone with Vietnam, Cambodia, Laos, Christmas Island, and Western Indonesia.
History
- Prior to 1 January 1901 locations in Siam with an astronomical observatory would adopt local mean time based on the observatory's geographic position. Chiang Mai Province 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 was adopted by Siam as the new standard time. The mean time of the 105th meridian is 7 hours ahead of Greenwich Mean Time.
- In July 2001, Thailand announced its intention of moving its time forward one hour, to align with both Malaysia and Singapore and more importantly with China and Hong Kong, i.e.,. This was met with much criticism and resistance and the plan was withdrawn.
| Period in use | Time offset from GMT | Name of time |
| 1 January 1880 - 31 March 1920 | Bangkok Mean Time | |
| 1 April 1920 – present | Indochina Time |