ISOWEEKNUM Function in Excel

ISOWEEKNUM function in Excel takes a date as input and returns a week number (1-54).

ISOWEEKNUM Function in Excel is similar to WEEKNUM Function but it follows ISO standards, where weeks begin on Monday and week number 1 is assigned to the first week in a year that contains a Thursday.

Syntax for ISOWEEKNUM Function in Excel

ISOWEEKNUM (date) 

date – The date for which you want to get the week number according to ISO standards.

 

Example of ISOWEEKNUM Function in Excel

Formula

ISOWEEKNUM Function in Excel 1

ISOWEEKNUM Functions does not consider 1/1/2016 as First week of the year.  It considers only from when the week starts with Monday and it should have Thursday in that week.

1/4/2016 which is Monday and has Thursday in that week, so 1/4/2016 is considered as first week. So the result will be

Result

ISOWEEKNUM Function in Excel 2

NOTE: ISOWEEKNUM function was introduced in Excel 2013 and so it is not available in earlier versions of Excel.

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