TZOVERLAP
First daily window when the local time is within [start,end) in ALL zones; [start,end] instants or 'No overlap'
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When to use it
When should I use TZOVERLAP instead of checking time zones manually?
Use TZOVERLAP when you need to find a single window where all participants across multiple time zones are simultaneously within business hours — it handles DST and date-line edge cases automatically.
What does TZOVERLAP return when no common window exists?
It returns the string "No overlap" when there is no moment in the given day where all listed zones simultaneously fall within the specified local time range.
How does the optional granularity_min parameter affect the result?
It controls the step size used when scanning the day for an overlap window; a smaller value (e.g., 5 minutes) gives a more precise start instant at the cost of more computation, while the default is typically 30 minutes.
Use cases
Locate an overlap for a US-UK logistics call within standard hours
Check for a narrow afternoon overlap with 15-minute precision
Used in
hr · operations · logistics
Syntax
TZOVERLAP(zones,start_local,end_local,date_serial,[granularity_min])