ISOWEEKNUM

ISOWEEKNUM(date)

Returns the week number in the year for a given date (based on European convention).

date

The date.

REMARKS

* This function returns a number between 1 and 54.
* This function returns the week number according to the European convention.
* The week number returned is according to the European ISO standard.
* All weeks start on a Monday and week number 1 is assigned to the first week that contains a Thursday.
* If "date" is not a valid date, then #VALUE is returned.
* If "date" is not a valid number, then #NUM is returned.
* You can use the NOW function to return the serial number of the current system date and time.
* You can use the TODAY function to return the serial number of the current system date.
* You can use the WEEKNUM function to return the week number in the year for a given date (based on US convention).
* This function was added in Excel 2013.
* For the Microsoft documentation refer to support.microsoft.com
* For the Google documentation refer to support.google.com

	A
1	=TODAY() = Friday, March 14, 2025
2	=NOW() = Friday, March 14, 2025, 05:09
3	=ISOWEEKNUM(A1) = 11
4	=ISOWEEKNUM(A1+7) = 12
5	=ISOWEEKNUM(A2+14) = 13
6	=ISOWEEKNUM("2023/2/20") = 8
7	=ISOWEEKNUM("1 Jul 2024") = 27
8	=ISOWEEKNUM(DATEVALUE("1 Jul 2024")) = 27
9	=ISOWEEKNUM(DATE(1, 1, 2024)) = 29

1 - What is the current system date. This cell has been formatted with the number format "dddd, mmmm dd, yyyy".
2 - What is the current system date and time. This cell has been formatted with the number format "dddd, mmmm dd, yyyy, hh:mm".
3 - What is the week number for the date.
4 - What is the week number for the date.