About World Clock

World Clock is a free tool for comparing the live local time of cities, states, provinces and countries around the world — on one screen, updating every second.

How the times are calculated

Accuracy comes first. Every clock, offset and time difference on this site is computed in your browser from the IANA Time Zone Database — the same rule set used by operating systems and airlines — through JavaScript's built-in Intl.DateTimeFormat API with real zone identifiers such as Asia/Karachi, America/New_York and Europe/London.

• No hardcoded offsets or differences. A zone's UTC offset is derived at the moment you look at it, so summer and winter answers differ correctly.
• Daylight saving is automatic. Spring and autumn clock changes, different transition dates per country, and regions that never change their clocks (for example Arizona and Pakistan) are all handled by the database rules.
• Database updates come with your browser. The IANA database ships with your browser and operating system and is refreshed when they update — this site never needs manual rule updates.
• No server calls for clocks. After the page loads, everything runs locally on your device.

Coverage

The built-in directory covers hundreds of cities across every continent — including every US state (with each of its time zones), all Canadian provinces and territories, UK cities, and capitals worldwide — plus the complete list of IANA time zones your browser knows, so any zone can be searched and added.

What the site is not

Times are shown for general information. For legal deadlines, flight times or broadcast schedules, always confirm with the official source. This site does not collect accounts, and your selected cities and preferences are stored only in your own browser.