World Clock: compare local times without doing the arithmetic
A world clock is only worth using if it stays correct during the few weeks a year when offsets are unusual. Here is how this page works, and the traps it is built to avoid.
What a world clock does that a converter does not
A world clock shows the current local time in several places at once, and keeps updating. A time zone converter answers a narrower question: given a date and a time in one zone, what is it in another? Both are useful, but the world clock is what you reach for before a recurring call rather than for a one-off calculation.
The difference matters because offsets are not fixed values. If you noted down that London is five hours ahead of New York last month, that number may be wrong this month. Both cities change their clocks, and they do it on different dates.
How to use this page
The page opens with twelve cities that together cover most working hours around the globe, from Auckland to Los Angeles. Each card shows the city name, its IANA identifier such as Europe/Berlin, the local time, the local date, and the difference from your own device clock.
Use the search box to add any city, country, or IANA zone identifier. Star a card to pin it to your favourites — favourites are stored in your browser, so they survive a refresh without an account.
Auto Update refreshes the display every second. Switching it off freezes the clocks, which is useful when you want to read one specific moment without the seconds moving.
Why the offset changes twice a year
Daylight saving time is decided country by country, and roughly seventy countries still observe it. The European Union switches at 01:00 UTC on the last Sunday of March and the last Sunday of October. The United States and Canada switch at 02:00 local time on the second Sunday of March and the first Sunday of November.
Those dates do not line up. For about three weeks each March, New York and London are four hours apart instead of the usual five, and the same gap opens again for roughly a week at the end of October. A meeting booked as “3pm in London, which is 10am in New York” quietly becomes 9am or 11am if it is booked inside one of those windows.
Some countries have stopped switching altogether: Russia in 2014, Turkey in 2016, Brazil in 2019, and Iran and most of Mexico in 2022. If your mental model of a country was formed a few years ago, it may already be out of date.
- In the southern hemisphere the seasons run the other way: Sydney and Auckland observe daylight saving from October to April, so their offset to Europe moves two hours a year in the opposite direction.
- Countries near the equator mostly do not switch at all, because their day length barely changes across the year.
Offsets that are not whole hours
Not every zone sits on a full-hour offset from UTC, and this is where mental arithmetic fails. India is UTC+05:30, Nepal UTC+05:45, Iran UTC+03:30, Afghanistan UTC+04:30, Myanmar UTC+06:30, Newfoundland UTC−03:30, the Marquesas UTC−09:30 and the Chatham Islands UTC+12:45. Lord Howe Island uses UTC+10:30 and shifts by only thirty minutes in summer.
These offsets are historical, usually chosen to put local noon close to the actual sun or inherited from railway and telegraph timetables. Whatever the reason, “just add three hours” gives the wrong answer in about a dozen places on Earth.
A reliable way to schedule across zones
Convert in a fixed order and most of the confusion disappears. First state the meeting in UTC, which has no daylight saving and never changes. Then convert from UTC into each participant’s zone using the date of the meeting, not today’s offset. Finally, re-check the day before.
Watch the date line. Auckland is twelve or thirteen hours ahead of UTC and Los Angeles seven or eight behind, which puts them twenty to twenty-one hours apart. A call at 9am Tuesday in Los Angeles is 5 or 6am Wednesday in Auckland — a different day, and outside most people’s working hours.
- If two participants are more than twelve hours apart, one of them is always outside 9-to-5. Rotate the inconvenient slot instead of asking the same region to get up early every time.
- When a DST change falls in the same week as the meeting, book it after the change, not before.
Who ends up using a world clock every day
Support teams handing a queue from Manila to Lisbon, engineers on a rotation split between Berlin and São Paulo, traders watching the Chicago open from Singapore, and anyone with family two continents away. The common thread is not travel — it is a recurring commitment at a fixed hour in somebody else’s day.