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 DATEVALUE function to return the date serial number given a date in text format.
* 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	B
1	=ISOWEEKNUM("1 Jan 2020") = 1	Wed, 1 Jan 2020
2	=ISOWEEKNUM("1 Jan 2021") = 53	Fri, 1 Jan 2021
3	=ISOWEEKNUM("1 Jan 2022") = 52	Sat, 1 Jan 2022
4	=ISOWEEKNUM("1 Jan 2023") = 52	Sun, 1 Jan 2023
5	=ISOWEEKNUM("1 Jan 2024") = 1	Mon, 1 Jan 2024
6	=ISOWEEKNUM("31 Dec 2020") = 53	Thu, 31 Dec 2020
7	=ISOWEEKNUM("31 Dec 2021") = 52	Fri, 31 Dec 2021
8	=ISOWEEKNUM("31 Dec 2022") = 52	Sat, 31 Dec 2022
9	=ISOWEEKNUM("31 Dec 2023") = 52	Sun, 31 Dec 2023
10	=ISOWEEKNUM("31 Dec 2024") = 1	Tue, 31 Dec 2024
11	=ISOWEEKNUM(TODAY()) = 18
12	=WEEKNUM(invalid_namedrange) = #NAME?

1 - What is the week number for 1 Jan 2020.
2 - What is the week number for 1 Jan 2021.
3 - What is the week number for 1 Jan 2022.
4 - What is the week number for 1 Jan 2023.
5 - What is the week number for 1 Jan 2024.
6 - What is the week number for 31 Dec 2020.
7 - What is the week number for 31 Dec 2021.
8 - What is the week number for 31 Dec 2022.
9 - What is the week number for 31 Dec 2023.
10 - What is the week number for 31 Dec 2024.
11 - What is the week number for the current date.
12 - If a named range is invalid, #NAME? is retrurned.