Online Tool Store
World Clock
See the current time in any set of cities side by side, each with its date and UTC offset, updating every second. Runs entirely in your browser.
This works right here on your device — nothing gets sent out.
Time converter
Pick a date and time in one city to see what it is in every clock above.
How it works
- Four clocks are shown to start with. Type a city or zone and press "Add clock" to add your own.
- Each card shows the local time, the date there, and the current UTC offset, refreshing every second.
- Switch to 24-hour time or hide seconds with the toggles; remove a city with ✕.
- To plan a call, use the Time converter: pick a city, enter a date and time there, and read it off for every other clock.
- Your list is remembered on this device, so the same clocks are waiting next time you open the page.
How the conversion is done
There is only ever one instant in time. Your device tracks it as a count of milliseconds since 1 January 1970 UTC, and a city's wall clock is that instant plus the region's offset:
local time = UTC instant + zone offset (at that instant)
The offset in brackets is the important part. It isn't a constant — Europe/London is UTC+0 in winter and UTC+1 in summer, and some regions have changed their rules outright. That's why each city is stored as an IANA zone name instead of a number: the browser looks up which offset applied at that exact moment, so the answer stays right across daylight saving changes and historical shifts.
It also explains the date line on each card. When London shows Tuesday morning, Tokyo is already nine hours ahead and can be on Tuesday evening, while New York is five hours behind and still on Monday night — same instant, three different calendar days.
FAQ
Where do the times come from?
Your own device. The clock reads your computer's current time and converts it into each zone using the time zone database built into your browser — nothing is fetched from a server, so no request is made and no list of the cities you watch is sent anywhere.
Does it handle daylight saving time?
Yes. Each city is stored as an IANA zone such as Europe/London rather than a fixed offset, so the displayed time and the UTC offset follow that region's daylight saving rules automatically, including on the changeover days.
Are my cities saved for next time?
Yes, in your browser's local storage on this device only — never on a server. Clearing site data or using private browsing resets the list to the defaults, and "Reset to defaults" does the same on demand.
What can I type in the search box?
Either a city name such as Paris or Colombo, or a full zone name such as Asia/Dubai. The dropdown lists every zone your browser knows, which is usually the complete IANA set of around 400 entries.
Why is my city missing?
The IANA database names one zone per region rather than per city, so smaller places share a nearby entry — Manchester is covered by Europe/London, and Bengaluru by Asia/Kolkata. Pick the zone your city belongs to and the time will be correct.
How do I convert a time between cities?
Use the Time converter under the clocks. Choose the city you are starting from, enter the date and time there, and every clock on your list shows the matching local time and date, with a +1 day or -1 day note when it lands on a different date.
What happens if I pick a time that does not exist because of daylight saving?
When clocks skip forward, some local times never happen — 2:30 am on 8 March 2026 in New York, for example. The converter tells you that time does not exist in that city instead of guessing. When clocks go back and a time happens twice, it uses the first occurrence.
Is the clock accurate to the second?
It's exactly as accurate as your device's own clock, which it re-reads every second. If your computer's time is off, every clock here is off by the same amount — most systems fix this themselves by syncing with a network time server.
How we compare
| Feature | Online Tool Store | World Time Buddy | Time-Conversion.com | 24timezones |
|---|---|---|---|---|
| Convert a chosen date and time across all your cities | Yes | Time slider | 24-hour timeline | Time converter tool |
| Custom list of cities and any IANA zone | Yes | Unlimited locations | Searchable city database | Custom city list |
| 12-hour and 24-hour display | Yes | Yes | Yes | Yes |
| Works with no account and no ads | Yes, no account, no ads | Free sign-in is optional; no ads | Not stated | No sign-in needed; ad-supported |
| Says when a time does not exist in daylight saving gaps | Yes | Not confirmed | Not confirmed | Not confirmed |
This covers the everyday questions — what time is it in Colombo, and what will 3 pm in London be for everyone on my list — on a tab you can glance at, with no ads and no record of who you're checking on. World Time Buddy also offers a visual time slider, saved settings with a free sign-in, share links and calendar export, which this tool doesn't.