World Clock and Time Zone Converter
Every place you care about, side by side, and the hours that suit all of them.
Runs entirely in your browser
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At another time
Meeting planner
Columns are hours in your own day. Green is inside working hours everywhere shown.
Add the places you deal with and see them all at once, each with its date, its offset from UTC and how far ahead or behind you it is. Somewhere in the middle of the night is shaded, so you can tell before you call.
Drag the slider to move every clock to the same future moment. The question is rarely "what time is it there" and usually "what time will it be there when I want to meet". The planner underneath answers the rest: a column for every hour of your day, green where it lands inside working hours everywhere shown, and a plain statement of which hours suit everybody.
Daylight saving is handled by your browser, which carries the full IANA time-zone database and its history of rule changes. The planner asks it for the offset at every hour separately, so a day containing a clock change still lines up correctly.
How to use it
- Pick a place and press Add clock. Your own zone is there already.
- Drag the slider to see the same moment at a different hour.
- Set your working hours and read off the columns that suit everyone.
Questions
Does it handle daylight saving?
Yes. Offsets come from your browser's copy of the IANA database, which knows each zone's rules and when they change. The planner queries the offset for every hour of the day separately, so a day that contains a spring-forward or fall-back still shows the right local times.
Why does a place show tomorrow's date?
Because it is tomorrow there. Anywhere far enough east crosses midnight before you do, and the clock says so rather than leaving you to work it out from the hour alone. Note that being hours ahead is not the same as being on the next day.
Why is there no hour that suits everyone?
Because the places you picked span more hours than your working day is long. Four zones spread across eighteen hours cannot all be at their desks at once, whatever hour you choose. Widen the working day, or accept that somebody joins early.
Are my clocks saved?
They are kept in your browser's local storage, so they come back on your next visit on the same device. Nothing is sent anywhere, and a page opened straight from a file may not be able to store them at all, in which case the defaults return each time.
What is UTC, and how is it different from GMT?
UTC is the reference all other zones are defined against, kept in step with atomic clocks. GMT is a time zone that happens to equal UTC in winter; Britain moves to UTC+1 in summer, so the two are not interchangeable. Use UTC for anything technical.
Your data stays on your device
Everything above runs inside your browser as WebAssembly compiled from Rust. Nothing you type is uploaded, logged or stored on a server. There is no server. You can load this page once, go offline, and it still works.