Working out what time it is for someone three zones away, while also accounting for whether they have switched to daylight saving, is a small headache that recurs constantly when your work or family is spread out. A world clock removes the arithmetic. Add the cities you care about to the world clock and read them all at once, with your own time anchored at the top.
It is free, runs in your browser with no sign-up, and the time-zone maths happens on your device, so nothing about your locations is sent anywhere.
Start from your own time
Your local time sits at the top, with the date and day of the week. That anchor matters: every comparison you make is “their time versus mine,” so having yours fixed and obvious means you never lose your footing while scanning the others.
Add the cities that matter
Pick cities from the list to add their current time, and add as many as you need. A remote team might track San Francisco, London and Singapore; someone with family abroad might keep two or three home cities pinned. The list is yours and it is remembered on your device, so it is waiting the next time you open the page. Remove any city with its close button when it stops being relevant.
Read them all at a glance
Each city shows its live time, its date, and its offset from you. When a colleague’s clock already reads tomorrow, you see it immediately rather than discovering it in a botched meeting invite. To find a slot that works for everyone, scan down the list for an hour that is daytime in every zone at once.
Why daylight saving is the quiet trap
The reason manual time-zone maths goes wrong is daylight saving. The gap between two cities is not fixed: it shifts when one of them springs forward or falls back, and the two often do it on different dates. A clock that uses your browser’s time-zone database applies those rules automatically, so the offsets it shows are correct for today, not for some average that is wrong twice a year. You do not have to remember who is on summer time; the clock already knows.
What it is good for
- Scheduling calls across zones. Find an hour that is reasonable for everyone before you send the invite.
- Keeping in touch with family. Know whether it is a good time to ring before you dial.
- Coordinating remote teams. See at a glance who is starting their day and who is finishing it.
- Planning travel. Read your destination’s time as you book connections.
Common mistakes to avoid
- Assuming the offset is constant. Two zones can be eight hours apart one month and nine the next because of daylight saving. Read the live offset, do not memorise it.
- Picking a city instead of a zone. Two cities can share a zone or differ; choose the actual place you mean so the daylight saving rules match.
- Coordinating by screenshot. Share the agreed moment in one named zone rather than a picture of your clock, so each person can read it correctly in their own.
Once you have settled on a moment with someone in another zone, the countdown timer lets you count down to it, and the alarm clock can nudge you when it arrives.