World Clock

How to use the world clock

Search for a city, tap a result to add it. Drag cards to reorder; tap the × to remove. The day/night map underneath updates in real time as the Earth turns.

Common questions

Why are some cities 30 or 45 minutes apart instead of a full hour?

A handful of regions chose non-hour offsets when their zones were set. India is at +5:30, Nepal at +5:45, parts of Australia at +9:30, parts of Newfoundland at -3:30. The world clock respects each location's actual offset.

Does it handle daylight saving automatically?

Yes. Cities that observe DST shift on their region's official date. Cities that don't (most of Asia, much of Africa, Arizona) stay put.

Can I share a layout with colleagues?

Add the cities you need, then copy the page URL. Anyone who opens it sees the same set of cities.

What does the shading on the map mean?

The dark side is the night half of the globe right now. The line between light and dark moves across the map in real time, so you can see who is in daylight before you message them.

Tips

Pin five to ten cities, not fifty. Past about ten, the list stops being a glance and turns into a lookup. Put your home zone first, then group the rest by region (Americas, then Europe, then Asia) so the order on screen matches the way you think about the world.

A brief history of time zones

The Earth rotates once every 24 hours, so the sun is high overhead in different places at different moments. Before the late 1800s every town set its own noon by the local sun. The result was a chaos that British railways solved in 1840 by adopting a single time across their network; the United States followed in 1883, and an international agreement in 1884 carved the globe into 24 hour-wide zones. About 38 are in use today, including a few at 30 and 45 minute offsets that never lined up with the round-hour grid.