Time zone overlap questions, answered
Answers to the questions people ask about scheduling across time zones: how overlap is found, why it moves twice a year, half-hour zones, and whether your data is stored.
What is a time zone overlap calculator?
It answers a question a time zone converter cannot: not "what time is it there", but "which hours of the day are all of us at work". You add each person's city and their working hours, and it returns the window — if any — where every one of those hours coincides.
How do I find overlapping working hours across time zones?
Add one row per person with their city and the hours they are contracted to work, then read the overlap at the top. Add as many people as you like; the window is the intersection of all of them, so it shrinks as you add cities. If it comes back empty, nothing is broken — it means there is no hour on that date when everyone is inside their own working day.
Why does the overlap change twice a year?
Because countries change their clocks on different dates. In most years the United States and the European Union are out of step for roughly two weeks in March and one week in October or November, and the southern hemisphere changes in the opposite direction. A converter that subtracts one local time from another is wrong during exactly those weeks. This tool works in absolute time, so it stays right.
What is the best time for a US and India team to meet?
For US Eastern and India, a 09:00 start in New York is 18:30 in India, so the only shared window sits early in the New York morning and late in the Indian evening. Running the overlap on a specific date gives you the exact minutes, and it will differ in the weeks when one side has changed clocks and the other has not.
How do I schedule meetings across time zones without frustrating people?
Pick the window where everyone is inside their working hours rather than the window that is most convenient for the majority, rotate the unpopular slot between regions so the same people are not always the ones on a 07:00 call, and keep recurring meetings inside the overlap so they survive a daylight-saving change without moving.
What about half-hour and 45-minute time zones?
India is UTC+05:30, Nepal is UTC+05:45 and the Chatham Islands are UTC+12:45. Any calculator that assumes whole-hour offsets gets these wrong by 30 or 45 minutes. This one works in minutes from UTC, so they are handled exactly.
Does the tool store my cities or send them anywhere?
No. Every calculation happens in your browser, and the cities you pick are never sent to a server. The only thing that persists is your light or dark mode preference, stored in your own browser. See the privacy page for the full detail.
Can I share the result with my team?
Yes. "Copy shareable link" puts the date, the cities and the working hours into the URL. Anyone who opens it sees the same overlap, in their own browser, with no account and no installation.
Is it free, and do I need an account?
It is free and there is no account, no email and no signup. The site carries advertising, which is what pays for the hosting.