Timezone Toolkit

Zones, Lookup, and Scheduling

TZ_WORKDAY_OVERLAP

Finds overlapping business hours between two zones.

Syntax

=TZ_WORKDAY_OVERLAP(zone1, zone2, [startHour], [endHour], [date])

Parameters

Namezone1
Typetext
DescriptionFirst IANA zone. The overlap is reported in this zone first.
Namezone2
Typetext
DescriptionSecond IANA zone.
NamestartHour?
Typenumber
DescriptionWorkday start hour from 0 to 23. Defaults to 9.
NameendHour?
Typenumber
DescriptionWorkday end hour from 1 to 24. Defaults to 17.
Namedate?
Typetext, number, or date
DescriptionReference date interpreted in zone1. Defaults to today.

Returns

A readable overlap string, such as "09:00-13:00 ... (4h)", or "No overlap".

Example

=TZ_WORKDAY_OVERLAP("America/New_York", "Europe/London", 9, 17, "2026-06-01")

Result: 09:00-12:00 America/New_York = 14:00-17:00 Europe/London (3h)

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