World Time Zones
When it’s lunchtime in New York, what time is it in Tokyo? Watch live world clocks, convert any time between cities and discover how time zones work.
Times come from your device’s clock and include daylight saving time where it applies.
| City | Local time | Difference |
|---|
Why time zones exist
The Earth spins once every 24 hours, so the Sun is overhead at different times in different places. Time zones keep “noon” close to when the Sun is highest.
15° = 1 hour
360° of longitude ÷ 24 hours = 15° per hour. In theory each zone is 15° wide, but borders bend to follow countries and states.
UTC
Coordinated Universal Time is the world’s reference clock, set at the Prime Meridian (0°). Zones are written as offsets, like UTC−5 or UTC+9.
East is ahead
Travel east and clocks move forward; travel west and they move back. Tokyo (UTC+9) sees sunrise many hours before London.
International Date Line
Roughly along 180° longitude in the Pacific. Cross it going west and you skip ahead a day; going east, you go back a day.
Daylight saving time
Many places move clocks forward one hour in spring and back in fall to get more evening daylight. Not every country — or U.S. state — does this.
U.S. time zones
The 48 connected states use Eastern, Central, Mountain and Pacific time; Alaska and Hawaii have their own zones.
Odd offsets
Some zones aren’t whole hours: India is UTC+5:30 and Nepal is UTC+5:45. China uses one time zone for the whole country.