Time Zone Calculator

UTC (Coordinated Universal Time) is the primary time standard by which the world regulates clocks. It's essentially the same as GMT but more precisely defined. All time zones are expressed as offsets from UTC (e.g., EST is UTC-5).

Time zones divide the Earth into 24 segments, roughly 15 degrees of longitude each. Moving east adds hours, moving west subtracts hours. When it's noon in London (UTC), it's 7 AM in New York (UTC-5) and 9 PM in Tokyo (UTC+9).

Daylight Saving Time (DST) advances clocks by 1 hour during warmer months to extend evening daylight. Not all regions observe DST. The US switches in March and November, while Europe changes in March and October.

Some countries chose offsets that don't align with hourly boundaries to better match their geographic position or for historical/political reasons. India (UTC+5:30), Iran (UTC+3:30), and Nepal (UTC+5:45) are examples.

The International Date Line runs through the Pacific Ocean at roughly 180° longitude. Crossing it westward adds a day; crossing eastward subtracts a day. It zigzags to keep island nations and territories on the same day.