What is a world clock?
A world clock shows the current local time in several places at once, so you can see at a glance whether it is a reasonable hour to call someone. Pick cities from the list above and they are added to the grid; your selection is saved on this device, so the same set is waiting for you next time.
Every time shown here is calculated from the IANA time zone database — the same authoritative dataset used by operating systems, airlines and booking systems. That means daylight saving transitions, historical rule changes and the awkward offsets are all handled for you rather than being approximated from a fixed UTC number.
How time zones actually work
The world is conventionally divided into zones offset from Coordinated Universal Time (UTC), the successor to Greenwich Mean Time and the reference against which every civil clock is defined. New York in winter is UTC−5; Tokyo is UTC+9. The difference between them — 14 hours — is why a 9am call in New York lands at 11pm in Tokyo.
The neat picture of 24 one-hour slices breaks down quickly in practice:
- Not every offset is a whole hour. India runs at UTC+5:30, Iran at UTC+3:30, and Nepal at UTC+5:45. Chatham Islands sit at UTC+12:45.
- Zones follow borders, not meridians. China spans roughly five geographic zones but uses a single one nationwide, so the sun rises well after 9am in the far west in winter.
- Daylight saving is not universal. Most of Europe and North America shift their clocks; most of Asia and Africa do not. Arizona stays on standard time while the rest of the United States moves, and Türkiye abandoned the switch entirely in 2016 in favour of permanent UTC+3.
- The southern hemisphere is out of phase. Australian summer time runs from October to April, so the gap between London and Sydney swings between 9, 10 and 11 hours over the course of a year.
This is precisely why a live world clock beats mental arithmetic. The offset you memorised last spring may not be the offset today.
Working across time zones
A few habits remove most of the pain of scheduling with people in other countries:
- Name the time zone, every time. "3pm" is useless in a message to another country; "3pm New York time (UTC−4)" cannot be misread.
- Look for the overlap, not the midpoint. Between Europe and the US west coast the only civilised window is roughly 4pm–7pm in Europe, which is 7am–10am in California.
- Beware the transition weekends. Europe and the United States change their clocks on different dates, so for two or three weeks each spring and autumn the usual difference is an hour off. Meetings scheduled by hand tend to break in exactly those weeks.
- Use dates, not weekdays, for anything near midnight. Friday evening in Los Angeles is already Saturday in Singapore.
- Rotate the pain. If a team spans Asia and Europe, someone is always taking the awkward hour. Alternating whose evening gets used is fairer than fixing it permanently on one side.
Frequently Asked Questions
Is daylight saving time handled automatically?
Yes. Times come from the IANA time zone database via your browser's built-in internationalisation support, so DST is applied correctly for each city, on that city's own schedule.
My city isn't in the list — what do I do?
Choose a nearby major city in the same zone. Any city sharing the zone shows an identical time, so Manchester behaves exactly like London and Osaka exactly like Tokyo.
Are the cities I add saved?
Yes, on this device only, in your browser's local storage. They are not uploaded anywhere and will not follow you to another device or survive clearing your browser data.
Why does the difference between two cities change during the year?
Because the two places start and end daylight saving on different dates — or because one of them does not observe it at all. The gap between London and New York holds at five hours most of the year but briefly becomes four during the weeks when only one has switched.
What is UTC?
Coordinated Universal Time, the global reference from which all civil time zones are defined as offsets. It does not observe daylight saving, which is why aviation, shipping and computer systems use it.
How accurate are these clocks?
They are derived from your device's system clock plus the correct zone offset, so they are as accurate as your device. With automatic time enabled, that is normally within a fraction of a second.
Current time by city
Open a dedicated live clock page for a single city: