How this world clock works
Times come from your device's clock combined with the official IANA time zone database built into your browser — the same database that operating systems, airlines, and financial systems rely on. That means daylight saving changes and government rule updates are always current without the site doing anything. An amber bar means it's daytime (6:00–20:00) in that city; a dark bar means night, so you can see at a glance who's awake. Your city list is saved on your own device and nowhere else.
Reading the clocks like a pro
Each card shows more than the time. The date line tells you whether that city is on the same day as you, or already on tomorrow (east of you across enough zones) or still on yesterday (far west, or across the date line). The UTC offset — like UTC+9 for Tokyo — is the city's distance from Coordinated Universal Time, the world's reference clock. Two cities' time difference is simply the difference of their offsets: Tokyo (UTC+9) minus New York (UTC−4 in summer) means Tokyo runs 13 hours ahead.
Why some cities surprise you
Not every zone is a whole hour. India runs on UTC+5:30, Nepal on UTC+5:45, and parts of Australia use half-hour offsets — so Mumbai can be 9½ hours ahead of New York. Big countries slice differently too: the continental United States spans four zones, China officially uses just one (all of it on Beijing time), and Russia crosses eleven. And because daylight saving is a political choice, not a natural one, the gap between two cities can change during the year: London and New York are usually 5 hours apart, but briefly 4 in late March, when the US has switched to summer time and the UK hasn't yet.
Frequently asked questions
How accurate are these clocks?
Exactly as accurate as your device's clock, which on phones and modern computers is synced automatically to network time and typically within a second of official time. The site adds no delay of its own — clocks tick locally in your browser.
Does it handle daylight saving time?
Yes, automatically, for every city — including places that don't observe DST at all (most of Asia and Africa) and southern-hemisphere countries whose summer time runs opposite to Europe and North America.
Can I use this offline?
Once the page has loaded, the clocks keep running without a connection — the time zone math happens entirely on your device.
Need to schedule across these zones? The converter translates a specific date and time between cities, and the meeting planner finds hours that work for everyone. Curious how zones came to be? Read time zones explained.