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.
|Period in use||Time offset from GMT||Name of time (unofficial)|
|1 January 1880 - 31 March 1920||UTC+06:42:04||Bangkok Mean Time|
|1 April 1920 – present||UTC+07:00||Indochina Time (ICT)|
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. The time was switched on 1 April 1920 at 00:00 (old time) to 00:17:56 (new time).
On 1 January 1990, the Cabinet of Thailand appointed the Royal Thai Navy as the official timekeeper for Thailand. Thai Standard Time is derived from five atomic clocks maintained by the Royal Thai Navy.
Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London, counted from midnight. At different times in the past, it has been calculated in different ways, including being calculated from noon; as a consequence, it cannot be used to specify a particular time unless a context is given.
A time zone is an area that observes a uniform standard time for legal, commercial and social purposes. Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude, because it is convenient for areas in frequent communication to keep the same time.
Universal Time (UT) is a time standard based on Earth's rotation. There are several versions of Universal Time, which differ by up to a few seconds. The most commonly used are Coordinated Universal Time (UTC) and UT1. All of these versions of UT, except for UTC, are based on Earth's rotation relative to distant celestial objects, but with a scaling factor and other adjustments to make them closer to solar time. UTC is based on International Atomic Time, with leap seconds added to keep it within 0.9 second of UT1.
Japan Standard Time, or Japan Central Standard Time, is the standard time zone in Japan, 9 hours ahead of UTC. There is no daylight saving time, though its introduction has been debated several times. During World War II, it was often called Tokyo Standard Time.
The 24-hour clock, popularly referred to in the United States and some other countries as militarytime, is the convention of timekeeping in which the day runs from midnight to midnight and is divided into 24 hours. This is indicated by the hours passed since midnight, from 0 to 23. This system is the most commonly used time notation in the world today, and is used by the international standard ISO 8601.
The Mountain Time Zone of North America keeps time by subtracting seven hours from Coordinated Universal Time (UTC) when standard time (UTC−07:00) is in effect, and by subtracting six hours during daylight saving time (UTC−06:00). The clock time in this zone is based on the mean solar time at the 105th meridian west of the Greenwich Observatory. In the United States, the exact specification for the location of time zones and the dividing lines between zones is set forth in the Code of Federal Regulations at 49 CFR 71.
The Alaska Time Zone observes standard time by subtracting nine hours from Coordinated Universal Time (UTC−09:00). During daylight saving time its time offset is eight hours (UTC−08:00). The clock time in this zone is based on mean solar time at the 135th meridian west of the Greenwich Observatory.
Central European Time (CET) is a standard time which is 1 hour ahead of Coordinated Universal Time (UTC). The time offset from UTC can be written as UTC+01:00. It is used in most parts of Europe and in a few North African countries. CET is also known as Middle European Time and by colloquial names such as Berlin Time, Brussels Time, Madrid Time, Paris Time, Rome Time, and Warsaw Time.
Time in the United States, by law, is divided into nine standard time zones covering the states, territories and other US possessions, with most of the United States observing daylight saving time (DST) for approximately the spring, summer, and fall months. The time zone boundaries and DST observance are regulated by the Department of Transportation. Official and highly precise timekeeping services (clocks) are provided by two federal agencies: the National Institute of Standards and Technology (NIST) ; and the United States Naval Observatory (USNO). The clocks run by these services are kept synchronized with each other as well as with those of other international timekeeping organizations.
Standard time is the synchronization 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 region, often near the center of the region. Historically, standard time was established during the 19th century to aid weather forecasting and train travel. Applied globally in the 20th century, the geographical regions became time zones. The standard time in each time zone has come to be defined as an offset from Universal Time. A further offset is applied for part of the year in regions with daylight saving time.
Time in New Zealand is divided by law into two standard time zones. The main islands use New Zealand Standard Time (NZST), 12 hours in advance of Coordinated Universal Time (UTC) / military M (Mike), while the outlying Chatham Islands use Chatham Standard Time (CHAST), 12 hours 45 minutes in advance of UTC / military M^ (Mike-Three).
The Newfoundland Time Zone (NT) is a geographic region that keeps time by subtracting 3+1⁄2 hours from Coordinated Universal Time (UTC) during standard time, resulting in UTC−03:30; or subtracting 2+1⁄2 hours during daylight saving time. The clock time in this zone is based on the mean solar time of the meridian 52 degrees and 30 arcminutes west of the Greenwich Observatory. It is observed solely in the Canadian province of Newfoundland and Labrador.
Singapore Standard Time (SST), also known as Singapore Time (SGT), is used in Singapore and is 8 hours ahead of UTC (UTC+08:00). Singapore does not currently observe daylight saving time.
Nepal Standard Time (NPT) is the time zone for Nepal. With a time offset from Coordinated Universal Time (UTC) of UTC+05:45 all over Nepal, it is one of only three time zones with a 45-minute offset from UTC.
UTC+07:00 is an identifier for a time offset from UTC of +07:00. In ISO 8601 the associated time would be written as 2021-07-29T12:20:01+07:00. It is 7 hours ahead of the UTC, meaning areas in this time zone would be 07:00 while UTC is shown to midnight (00:00).
Malaysian Standard Time or Malaysian Time (MYT) is the standard time used in Malaysia. It is 8 hours ahead of Coordinated Universal Time (UTC). The local mean time in Kuala Lumpur was originally GMT+06:46:46. Peninsular Malaysia used this local mean time until 1 January 1901, when they changed to Singapore mean time GMT+06:55:25. Between the end of the Second World War and the formation of Malaysia on 16 September 1963, it was known as British Malayan Standard Time, which was GMT+07:30. At 2330 hrs local time of 31 December 1981, people in Peninsular Malaysia adjusted their clocks and watches ahead by 30 minutes to become 00:00 hours local time of 1 January 1982, to match the time in use in East Malaysia, which is UTC+08:00. SGT (Singapore) followed on and uses the same until now.
The Wake Island Time Zone observes standard time by adding twelve hours to Coordinated Universal Time (UTC+12:00). The clock time in this zone is based on the mean solar time of the 180th degree meridian east of the Greenwich Observatory.
Coordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean solar time at 0° longitude and is not adjusted for daylight saving time. It is effectively a successor to Greenwich Mean Time (GMT).
Cambodia follows UTC+07:00, which is 7 hours ahead of UTC. The local mean time in Phnom Penh was originally UTC+7:19. Cambodia used this local mean time until 1920, when it changed to Indochina Time, UTC+07:00; ICT is used all year round as Cambodia does not observe daylight saving time. Cambodia shares the same time zone with Western Indonesia, Thailand, Vietnam, Christmas Island, and Laos.
Reunified Vietnam follows Indochina Time (ICT), which is seven hours ahead of UTC, ICT is used all year round as Vietnam does not observe daylight saving time. Vietnam shares the same time zone with Thailand, Cambodia, Christmas Island, Laos, and Western Indonesia.