Timezone Clock

About This Tool

The Timezone Clock displays the current time in multiple cities around the world simultaneously. It updates every second and shows each city's UTC offset and current date. This is useful for coordinating meetings across timezones, keeping track of business hours in different regions, or simply knowing what time it is wherever your colleagues, clients, or family members are located.

How Timezones Work

The Earth rotates 360 degrees in 24 hours, which means it moves 15 degrees per hour. Standard timezones divide the globe into 24 zones, each 15 degrees of longitude wide, centered on the Prime Meridian (0 degrees) at Greenwich, England. Moving east from Greenwich, each zone is one hour ahead; moving west, each zone is one hour behind. In practice, timezone boundaries follow political borders rather than strict meridian lines, which is why China uses a single timezone despite spanning five geographical zones.

Half-Hour and Quarter-Hour Offsets

Several countries use timezone offsets that are not whole hours from UTC. India Standard Time is UTC+5:30, covering the entire subcontinent. Nepal is UTC+5:45, making it the only major quarter-hour offset. Afghanistan is UTC+4:30, Iran is UTC+3:30, and Myanmar is UTC+6:30. Australia's central timezone (Adelaide, Darwin) is UTC+9:30. These fractional offsets exist because the countries chose offsets that better align with their solar noon, rather than rounding to the nearest full hour.

Daylight Saving Time

Daylight Saving Time (DST) shifts clocks forward by one hour in spring and back in fall, extending evening daylight during summer months. About 70 countries observe DST, but the dates vary. The US and Canada change in March and November. The EU changes in March and October. Countries near the equator generally do not observe DST because day length varies little throughout the year. Australia and parts of South America observe DST on the opposite schedule (their summers are the Northern Hemisphere's winters), which means the time difference between, say, New York and Sydney changes four times per year.

Tips for Working Across Timezones

When scheduling across timezones, always specify the timezone explicitly (for example, "3 PM EST" or "15:00 UTC"). Avoid using abbreviations that are ambiguous: CST could mean Central Standard Time (US), China Standard Time, or Cuba Standard Time. UTC is the safest universal reference. For recurring meetings, rotate the time burden so the same people are not always inconvenienced. Tools like this timezone clock help you quickly visualize what time it is everywhere and find windows that work for all participants.