Understanding Time Zones: A Complete Guide

What are time zones?

Time zones are imaginary strips that divide the Earth into 24 zones, each with a different hour. This system was created in 1884 during the International Meridian Conference in Washington to standardize times around the world.

How did time zones come about?

Before time zones, each city set its own time based on the position of the sun. With the expansion of railways and the telegraph in the 19th century, it became impossible to maintain hundreds of different local times. Sir Sandford Fleming, a Canadian engineer, proposed dividing the Earth into 24 zones of 15 degrees each.

The Greenwich Meridian (GMT)

The reference point is the Greenwich Meridian (longitude 0°), which passes through the Royal Observatory in London. From there, time zones advance eastward (GMT+1, GMT+2, etc.) and go back westward (GMT-1, GMT-2, etc.).

How to calculate time differences

To find out what time it is in another country, simply check the difference between time zones. For example, if it's 3 PM in New York (GMT-5) and you want to know the time in Tokyo (GMT+9), the difference is 14 hours: it's 5 AM the next day in Tokyo. Use our time comparison tool to make this easy!