Multi-Timezone Meeting Planner

How Multi-Timezone Meeting Planner Works

Scheduling a meeting across three or more time zones by mentally adding and subtracting UTC offsets is where scheduling mistakes creep in -- especially since offsets themselves shift with daylight saving time in some regions but not others. This planner lays out every zone's local time side by side across a full 24-hour UTC grid and highlights exactly which hours fall inside everyone's working hours at once.

Formula & Method

For each hour of the chosen date (in UTC), the tool converts that instant into each zone's local wall-clock time using the browser's built-in Intl.DateTimeFormat API, which correctly accounts for each zone's current UTC offset and daylight saving rules for that specific date -- not a fixed offset that would be wrong for half the year in regions that observe DST. An hour counts as "working" for a zone if the local hour falls within your specified working-hours range, and an hour is a true overlap only if every single zone in your list is simultaneously working at that UTC hour.

Worked Example

With the default zones (Eastern Time, London, Tokyo) and 9am–5pm working hours in each, the only UTC hours where all three zones are simultaneously in their working window are typically a narrow morning band -- illustrating why distributed teams spanning the US, Europe, and Asia often have just an hour or two of genuine overlap, not a full workday's worth.

Frequently Asked Questions

Why does the tool need a specific date, not just time zones?

Time zone offsets aren't fixed year-round -- daylight saving time shifts many zones' UTC offset by an hour for part of the year, and not every zone observes DST or switches on the same date. Anchoring the calculation to one specific date ensures the local times shown (and therefore the overlap) are correct for that day, rather than assuming a year-round offset that could be off by an hour depending on the season.

Why do some rows show "+1" or "−1" next to the time?

Because a single UTC hour can fall on a different calendar date depending on the zone -- for example, 2am UTC is already the next day in zones far ahead of UTC, and still the previous day in zones far behind it. The +1/−1 marker flags when a zone's local time has crossed into the next or previous day relative to the date you selected, which matters for correctly telling colleagues "your Tuesday morning" vs. "your Monday night."

What if there's no overlap at all between the zones I've chosen?

The tool reports "No overlap found" rather than guessing at a compromise -- this genuinely happens with working-hours-only constraints across zones on opposite sides of the globe (e.g., US Pacific and Australia), and the honest answer is that someone needs to meet outside standard working hours, which is useful information on its own.

Can I add more than three time zones?

Yes, up to 6 at once (with a minimum of 2) -- useful for larger distributed teams, though as you add more zones spanning a wider spread of the globe, the overlap window (if any exists) tends to shrink correspondingly, since every added zone is another constraint the "All Available" row has to satisfy simultaneously.