Convert time between any two time zones. See what time it is right now in cities around the world.
Why do time zones exist?
Before standardized time zones, every city kept its own local time based on when the sun was directly overhead (solar noon). This made coordinating trains, telegraphs, and communication between cities extremely difficult. In 1884 the International Meridian Conference established the system of 24 time zones we still use today, centered on the Greenwich meridian (0°).
New to this? Here's the simple version
Think of Earth as a clock divided into 24 slices. As the Earth rotates, different slices face the sun at different times. When it's noon in New York, it's already 6pm in London and 1am the next day in Tokyo. Time zones let everyone in the same region share a common clock rather than each city having a slightly different time.
What is UTC?
UTC (Coordinated Universal Time) is the global time standard. All other time zones are defined as offsets from UTC — for example, Eastern Time is UTC-5 (or UTC-4 during daylight saving time). UTC replaced GMT (Greenwich Mean Time) as the primary standard in 1960.
What is daylight saving time?
Daylight saving time (DST) is the practice of moving clocks forward by one hour in spring and back in fall to make better use of daylight. Not all countries observe DST — Arizona (US), most of Africa, and parts of Asia do not change their clocks.
What's the best time for international meetings?
This depends entirely on the time zones involved. A common strategy is to find a time that falls within business hours (9am-5pm) for as many participants as possible. Someone will usually have to compromise — early morning or late evening meetings are common for cross-continental calls.