When local work hours sit on different dates
A work window is always that person’s local start and end. HourAlign converts those clocks into real instants, so the baseline date and someone else’s local date do not have to match.
Local hours stay local
Type 09:00–17:00 for Auckland and you mean nine to five in Auckland, not nine to five in the first city.
The planner tests every instant of the first city’s local date against each person’s actual local date and time at that instant.
Dates in the result can disagree
Auckland on Tuesday morning can line up with Los Angeles on Monday afternoon. The result lists each person’s local date and clock, and labels next-day or previous-day shifts instead of hiding them.
The first city only chooses that local day’s span of real time. It does not force everyone else onto that civil date.
Same-day start before end
Each person currently has one window, and start must be earlier than end on that local day. Overnight and split shifts are out of scope for this version.
Invalid hours are rejected with an error you can fix. They are not silently wrapped past midnight.
How to read an empty or short result
“No common work window” means the entered hours never overlap on that baseline date. It is not a statement about anyone’s real calendar.
A separate result means the hours do overlap, but no single stretch is long enough for the meeting length you picked. Shorten the meeting or adjust a window; the tool will not pretend a 30-minute gap holds a 60-minute meeting.
Example
Put Auckland first, date 2026-09-29, 09:00–17:00. Add Los Angeles 09:00–17:00. Part of Auckland’s Tuesday morning is still Monday in Los Angeles.
Add a third person in London if you want a three-way check. Use 2 to 8 people; the first city remains the baseline.