World Clock

How to use the world clock

1. At the top, Your time shows the time in your own time zone, as detected by your browser.
2. In Add a city or time zone, type a city such as “Montreal”, “Tokyo” or “São Paulo”, or an IANA time zone such as Asia/Kolkata, then press Add (or Enter). Suggestions appear as you type, in English or French, with or without accents.
3. Each card shows the live time, the date, the UTC offset, whether the city is on daylight saving time or standard time, how far ahead or behind you it is, and whether it is day, twilight or night there.
4. Remove a city with Remove, reorder the list from west to east with Sort by UTC offset, or go back to the starting list with Restore default cities. Tick 12-hour clock (AM/PM) if you prefer that format.

Your list of cities and your clock format are saved in this browser only, so they are there the next time you open this page.

Where the time comes from

This tool doesn’t look up the time of a city on a server. It uses a curated list of about 240 major cities, each mapped to one IANA time zone: Montreal, Ottawa and Quebec City map to America/Toronto, Mumbai and New Delhi to Asia/Kolkata, Geneva to Europe/Zurich. The time itself, the UTC offset and the daylight saving time rules then come from the time zone database built into your browser, through the standard Intl API.

That design has two consequences. First, the clocks are as accurate as your device’s clock: if your computer is two minutes off, every city will be two minutes off too. Second, when a country changes its time rules, the change reaches you with your next browser or operating system update, not through this page.

If a city isn’t in the list, add its time zone directly. Every IANA zone your browser knows is accepted, from Pacific/Chatham (UTC+12:45 in standard time) to America/St_Johns (UTC−03:30).

Day, night and twilight

The day/night indicator isn’t a simple “6 a.m. to 6 p.m.” rule. For cities in the list, the tool computes the sun’s elevation from the city’s approximate coordinates and the current moment:

• Daytime (sun up): the sun is above the horizon.
• Twilight (dawn or dusk): the sun is less than 6° below the horizon (civil twilight), when it is still light outside.
• Night: the sun is more than 6° below the horizon.

So Helsinki shows daytime late into a June evening, and Singapore switches to night at nearly the same hour all year. For a bare time zone without a city, the tool falls back to 06:00–18:00 local time.

Reading the offsets

The offset shows how far the local clock is from Coordinated Universal Time (UTC). Offsets change with daylight saving time: London is at UTC in winter and UTC+01 in summer. Some offsets aren’t whole hours: India is at UTC+05:30 and Nepal at UTC+05:45. “Yesterday for you” or “tomorrow for you” means the calendar date there differs from yours.