World Clock
See the current time in major cities around the world. Live updating with seconds, automatic DST adjustment.
Understanding World Time Zones
The world is divided into 24 standard time zones, each roughly 15 degrees of longitude wide. The system was established in 1884 at the International Meridian Conference in Washington, D.C., with Greenwich, England designated as the prime meridian (0° longitude).
How Time Zones Work
- 1 Earth rotates 360° in 24 hours = 15° per hour
- 2 Each time zone covers approximately 15° of longitude
- 3 UTC (Coordinated Universal Time) is the reference point
- 4 Zones east of UTC are ahead (+), west are behind (-)
- 5 Some regions use half-hour or quarter-hour offsets
Key Time Standards
Coordinated Universal Time
Global reference
Greenwich Mean Time
UK winter time
Daylight Saving Time
+1 hour seasonal
Not all countries observe Daylight Saving Time. Countries near the equator typically don't change their clocks because day length doesn't vary significantly throughout the year.
Frequently Asked Questions
What is a World Clock?
A World Clock displays the current local time in multiple cities and time zones around the world simultaneously. It automatically accounts for time zone differences and Daylight Saving Time (DST) changes, making it easy to know what time it is anywhere in the world.
How many time zones are there?
There are 24 standard time zones, but with half-hour and quarter-hour offsets (like India at UTC+5:30 and Nepal at UTC+5:45), there are over 37 distinct UTC offsets in use worldwide. This is why some cities show times that are 30 or 45 minutes different from their neighbors.
Does this clock adjust for Daylight Saving Time?
Yes! Our World Clock uses the IANA time zone database built into modern browsers (via the Intl API), which automatically handles DST transitions. When a city's clocks change, the displayed time updates automatically — no manual adjustment needed.
How accurate is this World Clock?
The clock uses your device's system time and the browser's Intl.DateTimeFormat API for precise time zone calculations. It updates every second and is as accurate as your device's system clock. For best results, ensure your device syncs with an NTP time server.
What is the difference between GMT and UTC?
GMT (Greenwich Mean Time) and UTC (Coordinated Universal Time) are often used interchangeably, but they differ technically. UTC is based on highly precise atomic clocks and is the modern global time standard. GMT is based on astronomical observations at the Royal Observatory in Greenwich, England. For everyday use, they are effectively identical.
Can I switch between 12-hour and 24-hour format?
Yes! Click the "12H" / "24H" toggle button at the top of the clock to switch between 12-hour (AM/PM) and 24-hour (military) time format. Your preference is saved in your browser for future visits.