Excel ISOWEEKNUM Function

What is ISOWEEKNUM function in Excel?

The ISOWEEKNUM function is one of the Date & Time functions of Excel.

It returns the ISO week number in the year for a given date.

We can find this function in Date & Time of insert function Tab.

How to use ISOWEEKNUM function in excel

1. Click on an empty cell (like F5).

2. Click on the fx icon (or press shift+F3).

3. In the insert function tab you will see all functions.

4. Select Date & Time category.

5. Select ISOWEEKNUM function

6. Then select ok.

7. In the function arguments Tab you will see ISOWEEKNUM function.

8. Date is the date-time code used by Microsoft Excel for date and time calculation.

9. You will see the result in the formula result section.

Examples of ISOWEEKNUM function in excel

example 1:

How to calculate Number of the week in the year in Excel?

In the following example, as you can see in the photo, Number of the week in the year can be identified by the ISOWEEKNUM function.

=ISOWEEKNUM("01/02/1900")----->>>>answer is  1
=ISOWEEKNUM("1-Jan-2020")----->>>>answer is  1
=ISOWEEKNUM("2-Jul-2020")----->>>>answer is  27
=ISOWEEKNUM("3-Sep-2021")----->>>>answer is  35
=ISOWEEKNUM("4-Apr-2022")----->>>>answer is  14

What is the purpose of ISOWEEKNUM function?

It returns the ISO week number in the year for a given date.

What is the Return value  of ISOWEEKNUM function?

It returns a positive number.

=ISOWEEKNUM("Date")----->>>>Number

How many arguments does ISOWEEKNUM function have?

=ISOWEEKNUM("Date")----->>>>Number

This function has just 1 Argument.

The argument of ISOWEEKNUM function is date.

The argument of ISOWEEKNUM function is required and not optional.

Which version of excel supports ISOWEEKNUM function?

This function is available for all excel versions (2003-2019)

Errors in ISOWEEKNUM function

If the date argument is not a valid number, ISOWEEKNUM returns the #NUM! error value.

If the date argument is not a valid date type, ISOWEEKNUM returns the #VALUE! error value.

ISOWEEKNUM related functions

• Use WEEKNUM function to return the week number in the year.
• Use WEEKDAY function to return a number from 1 to 7 identifying the day of the week of a date.