Multi-Timezone Working-Hours Overlap Finder

Find meeting windows where everyone is awake and on the clock — across 2 to 6 time zones.

What it does. You list each participant with their city (or IANA timezone, like America/Sao_Paulo) and their local working hours. The tool converts every participant's working window to UTC, finds the intersection where all of them are simultaneously working, removes lunch breaks, filters by shared working days, and ranks the resulting slots by how "civilized" the local time is for each person (nobody should be asked to join at 23:00).

How it ranks slots. Each overlap window gets a comfort score: the more participants for whom the slot falls inside 09:00–17:00 local, the higher it ranks. Slots that push anyone past 20:00 or before 07:00 local are flagged with a ⚠️ warning.

DST is handled. The tool uses the browser/runtime IANA timezone database via Intl.DateTimeFormat, so daylight saving transitions are respected for the week you analyze. Always pick the Monday of the week you care about — the analysis runs for 7 days from that date.

Export to calendar. The .ics file contains one all-day-style event per day for each overlap window, so you can drop it straight into Google Calendar / Outlook / Apple Calendar and see candidate times at a glance. Invitees are listed in the event description.

Tips.

• If there's no overlap at all, try widening one person's hours by an hour, or switch a 5-day to a 6-day work week.
• For US–Europe–Asia triads, the overlap is almost always in a narrow morning-UTC window; expect short slots.
• City names that aren't recognized? Use the IANA key instead (Asia/Kolkata, Europe/Berlin, America/New_York).