Let the shift stay together
An availability window from 22:00 to 06:00 begins in the evening and ends on the next local date. If Monday is selected, it means Monday 22:00 through Tuesday 06:00. Tuesday’s morning tail belongs to the Monday-start window. The Tuesday checkbox controls whether another shift starts on Tuesday evening.
Convert both boundaries before looking for overlap
Consider New York on Monday, 26 October 2026, with availability from 22:00 to 06:00. Under the bundled rules, that interval is 02:00–10:00 UTC on Tuesday. London’s Tuesday 09:00–17:00 availability is 09:00–17:00 UTC. Their common interval is therefore 09:00–10:00 UTC.
| Place | Local shared interval |
|---|---|
| New York | Tuesday 05:00–06:00 |
| London | Tuesday 09:00–10:00 |
Fit the full duration inside the tail
A 45-minute call starting at 05:00 New York is 09:00–09:45 London and fits both windows. The latest start for that duration is 05:15 New York or 09:15 London. A 90-minute call cannot fit the one-hour intersection, even though its start would be within both schedules.
Include the day before a search boundary
If the visible seven-day range begins on Tuesday, Monday’s overnight interval may still contribute useful Tuesday hours. A calculation that looks only for shifts starting inside the visible range would miss that tail. The interval needs to be considered whenever it overlaps the requested time range.
Keep clock changes in view
An overnight interval can cross a clock change. Its elapsed length may differ from a simple subtraction of two wall-clock labels. The planner maps availability onto real UTC segments: a skipped wall-clock portion contributes no time, and a repeated portion can include both occurrences. A selected meeting start inside a repeated interval still needs an explicit earlier-or-later choice.
Confirm the person’s real availability
A night shift is a useful example, not a statement about an entire city’s work pattern. Ask whether the morning tail is actually available for a call, and keep breaks or handover duties in mind. The tool can show an intersection only for the hours you provide.
Sources
Follow the original references for the rules and formats used in this guide.