Bangkok Time Now
Bangkok, Thailand follows an offset in time which subtracts 7 hours from the Coordinated Universal Time (UTC). This means that it is seven hours ahead of the UTC and Greenwich Mean Time (GMT). Originally, the local mean time in Bangkok used to be GMT + 06:42:04. It was operational until 1920 when it was changed to GMT + 07:00, Indochina Time. Before 1901, the locations in Siam would adopt the local mean time with an astronomical observatory according to the geographical position of the observatory. Chiang Mai Province and had an observatory as well as two other provinces. They both had a distinct local mean time and the three locations were separated with minutes of difference
A new standard time was adopted by Siam on April 1920 and was referred to as the mean time of the 105th meridian east. This time Zone is considered to be ahead of the Greenwich Mean Time by UTC + 7:00. This refers to the local mean time near London, the United Kingdom at the Greenwich Royal Observatory. On March 1920, the clocks in Thailand were adjusted ahead by 17 minutes, 56 seconds to use the time in Southeast Asia i.e. UTC+07:00:00 and UTC +06:42:04 ahead of GMT. The new time was switched to 06:17:56 and Thai Standard time is maintained by the Royal Thai Navy, having been derived from five atomic clocks.