🌍 World Clock
Track time across multiple cities. Search, add, and monitor local times worldwide — instantly and free.
🌎 No cities added yet
Search for a city above to add it to your world clock.
📋 When to Use the World Clock
- Remote teams across time zones — Instantly see what time it is for your colleagues in San Francisco, Berlin, or Bangalore before scheduling a meeting.
- International travel planning — Compare departure and arrival city times side by side to avoid jet lag surprises and missed connections.
- Global client calls — Check if it's business hours in London, Tokyo, or Dubai before picking up the phone.
- Following live events worldwide — Track event start times across continents — F1 races, product launches, or conference keynotes.
- Family and friends abroad — Keep an eye on local time for loved ones in different countries so you never call at 3 AM.
⚙️ How the World Clock Works
The World Clock uses your browser's built-in Internationalization API (Intl.DateTimeFormat) to compute accurate local times for any IANA timezone. When you add a city, the tool stores the city name and its associated timezone identifier (like America/New_York or Asia/Tokyo) in localStorage. A single JavaScript interval runs once per second, iterating through all added cities and rendering the current time, date, day/night indicator, and UTC offset for each one. The day/night detection checks whether the current hour falls between 6 AM and 6 PM local time and styles each clock card accordingly. No external APIs are called — all computation happens instantly in your browser, making it privacy-first and offline-capable.
The autocomplete search uses a curated list of over 400 cities worldwide, each mapped to its correct IANA timezone. As you type, the list is filtered by a case-insensitive substring match against city names and country identifiers. The dropdown supports keyboard navigation — you can arrow through results and press Enter to select. Your city selection persists automatically in localStorage, so when you return to the page, your configured clock list is right where you left it.
How to Use the World Clock
- Search for a city — Start typing a city name in the search box at the top. The autocomplete dropdown shows matching cities with their timezone identifiers.
- Select a city — Click a city from the dropdown list, or use the arrow keys and press Enter to add it to your clock grid.
- View live times — Each clock card displays the current local time in 24-hour format, today's date, the UTC offset, and a colored dot indicating day (blue) or night (purple). Cards with a blue left border are in daytime; dark-bordered cards show nighttime.
- Add more cities — Repeat the search to add as many cities as you need. Cities are saved automatically in localStorage.
- Remove a city — Click the ✕ button in the top-right corner of any clock card to remove it from your list.
Frequently Asked Questions
How do I add a city to the world clock?
Start typing a city name in the search box at the top of the page. A dropdown list of matching cities appears — click any city to add it to your clock grid. The tool includes over 400 cities worldwide, from major capitals to regional hubs.
Does the world clock update automatically for daylight saving time?
Yes — the World Clock uses your browser's IANA timezone database, which includes all daylight saving time rules. When a city enters or exits DST, the displayed time updates automatically. You never need to adjust anything manually.
Can I use the world clock offline?
Yes. Since all time computation runs in your browser using the Intl.DateTimeFormat API, no internet connection is needed once the page loads. Your saved cities are stored in localStorage and persist across sessions.
How many cities can I add at once?
There is no hard limit — you can add as many cities as you like. The grid layout automatically adjusts to fit your screen, displaying cards in responsive columns. Performance remains smooth even with 50+ cities.
Why does my city show a different time than I expected?
Each city is mapped to its official IANA timezone. Some large countries span multiple time zones (e.g., the US has Eastern, Central, Mountain, and Pacific). Make sure you selected the correct city — for example, "Los Angeles" (Pacific) is different from "New York" (Eastern).
Is the city list complete for my country?
The built-in list covers over 400 cities across all major time zones worldwide. If your specific city isn't listed, search for the nearest major city in the same time zone — the local time will be identical.
Does the world clock work on mobile phones?
Absolutely. The World Clock is fully responsive and works on all modern smartphones and tablets. The clock grid stacks into a single column on small screens for easy reading.
How accurate is the world clock compared to atomic time?
The displayed time is sourced from your device's system clock, which most modern operating systems synchronize with internet time servers (NTP). Accuracy is typically within a few hundred milliseconds of official atomic time.