In 1847, the British railroads accepted GMT as a standard.

GMT was the same as Universal Time up until 1972. To calculate the time zone an area theoretically falls in, the measurement of the area’s longitudinal coordinate is divided by 15. This means that, in the spring, a clock will go from 4:00 Standard Time to 5:00 DST. World Clocks are adjusted forward by one hour in the early spring and then set back by one hour in the autumn. Therefore, for half of the year some countries adjust their clocks by one hour.

For instance, Saudi Arabia, which is 3 hours ahead of the UK, has a time zone of “GMT +3” and Colombia, which is 5 hours behind the UK, has a time zone of “GMT -5”.ĭaylight Savings Time (DST) is practiced in certain parts of the world in order to allow for more hours of daylight during the working day. The UK sets the standard for Greenwich Mean Time at “ GMT 0” and other countries can calculate their time zone in accordance with how many hours they are ahead of or behind the UK. There are 24 different time zones on earth to correlate with the 24 hours in each day and which are displayed in our time zone map here at World Clock. Time zones are regions of the earth divided by lines of longitude. However, there is no actual time difference between GMT and UTC and therefore the two can be used interchangeably. There are two standards by which a country’s time zone is categorized the older of the two standards is Greenwich Mean Time (GMT) and the more modern of the two standards is Coordinated Universal Time ( UTC). Whether you’re looking to book a flight, schedule an international teleconference, use our time zone converter or our time zone map and observe the trading hours of an overseas business, can show you the time in a matter of seconds. With incomparable time-telling precision, World Clock is the perfect point of reference for travelers and business people alike. provides accurate world time, statistics and weather in major cities across the world.

World clock time converter