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What is the full form of GMT

GMT: Greenwich Mean Time

GMT stands for Greenwich Mean Time. It is the mean solar time at the royal observatory in Greenwich London. It is measured on the zero degree line of longitude of the Earth (meridian). This line runs from the North Pole to South Pole, i.e. passes through the Old Royal Observatory, Greenwich in London.

Greenwich Mean Time is a global time standard. It was established in the year of 1884 and used as a standard to scale all the time in the world. It is used as a benchmark for all time zones.

Sometimes, Greenwich Mean Time is known Greenwich Meridian Time because it is measured from the Greenwich Meridian Line. It is based on the rotation of the earth which is irregular but it follows a fictitious mean and considers a uniform speed along the equator.

Greenwich Mean Time is an international time. It is the basis of world time. This is a absolute time reference. It doesn't change with season. If a country is located to the east of the Greenwich Meridian, its local time is ahead of GMT, e.g. the local time of China is GMT+8 hours. Similarly, if a country is located to the west of Greenwich Meridian, its local time is behind the GMT, e.g. the local time of New York is GMT ? 4 in summer and GMT -5 hours in winter.

GMT full form

Longitude and Latitude of Greenwich

Longitude of the Greenwich Mean Time is 0º 0' 0" and Latitude of the Greenwich Mean Time is 51º 28' 38"N (North of the Equator).


  • Until 2 August 1880, it was not adopted officially by the British Parliament.
  • On 18 November 1883, it was adopted by the United States (USA).
  • GMT was internationally adopted in 1884 in the International Meridian Conference and 24 time zones were created.
  • Today, it is used as the UK's civil time or UTC.
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