WEEKNUM_OOO calculates the week number of the year for the internal date value.

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This function exists for interoperability with LibreOffice releases older than 5.1.0 and OpenOffice.org. It calculates week numbers for a week numbering system in that week number 1 is the week that contains the January 4th. This function does not provide interoperability with other spreadsheet applications. For new documents use the WEEKNUM or ISOWEEKNUM function instead.


WEEKNUM_OOO(Number; Mode)

Number is the internal date number.

Mode sets the start of the week and the calculation type.

1 = Sunday

2 = Monday (ISO 8601)

any other value = Monday (ISO 8601)


=WEEKNUM_OOO(DATE(1995;1;1);1) returns 1

=WEEKNUM_OOO(DATE(1995;1;1);2) returns 52. Week 1 starts on Monday, 1995-01-02.