Free tool
What time is that in their city?
Type a time once. Every city you added updates.
Source zone
09:00
New York
14:00
London
18:30
Kolkata
How to convert a time
Search a city and add it. The search uses IANA time zone names, so New York is America/New_York and London is Europe/London.
Pick the source zone, then type the local date and time in that city. The other rows show the same moment.
Remove a city with the control on its row. The list updates in this browser immediately.
The first visit shows New York, London, and Kolkata. Those three are a starting list, not a guess about where you are.
When to use it
Planning a call is one time typed once. Each person reads their own row instead of doing the offset by hand.
Writing a time into a document is the same view. You can copy the hour you see next to their city.
Checking a teammate's city does not require leaving the page. Add the city, leave it, and it is still here when you come back in this browser.
A meeting across cities
Type the local time in the city where the meeting is held. Each other row shows that same moment in the city you added. The list stays in this browser.
Questions
Do I need an account?
No. The conversion runs in your browser. OnlyBusy does not receive the cities or the time you type, and there is no signup.
Where is the city list stored?
The cities you add stay in localStorage on this browser, under a key this page owns. Another browser, or a cleared site storage, starts again from New York, London, and Kolkata.
Does daylight saving change the result?
Yes. Each city is an IANA time zone, so the offset includes daylight saving for the date you picked. A 09:00 in New York is 14:00 in London both in October, when New York is on daylight time, and in January, when both cities are on standard time.
Writing a private Busy block into someone else's Outlook or Google calendar is a different job, covered in show busy on Google Calendar and Outlook without sharing the event.