World Clock - Multiple Timezone Display
View the current time across multiple cities and time zones simultaneously. Add, remove, and compare times around the world instantly.
Runs in your browser. No data leaves your device.
Frequently Asked Questions
How does the World Clock work?
A one-second interval updates a shared Date object. Each clock card passes its IANA timezone string (e.g. "America/New_York") to Intl.DateTimeFormat, which uses the browser's built-in IANA/Olson timezone database to format the time and date. DST transitions are handled automatically by the Intl API. Offset labels are extracted from formatToParts with the shortOffset style.
How many time zones can I display at once?
There is no hard limit. Add as many cities as you need and they all display simultaneously with live-updating times.
Does it account for daylight saving time?
Yes. The tool uses your browser's built-in timezone database (IANA/Olson), which automatically handles DST transitions for all supported time zones.
Can I compare a specific time across zones?
Yes. The clocks show the current time in each zone side by side, making it easy to find overlapping work hours or schedule meetings across time zones.