How to Use the ISOWEEKNUM Function in Excel: Usabilities, Examples, and Writing Steps - Compute Expert

How to Use the ISOWEEKNUM Function in Excel: Usabilities, Examples, and Writing Steps


Home >> Excel Tutorials from Compute Expert >> Excel Formulas List >> How to Use the ISOWEEKNUM Function in Excel: Usabilities, Examples, and Writing Steps





In this tutorial, you will learn how to use the ISOWEEKNUM function in excel completely.

When working with dates in excel, we may sometimes need to get the week number of our date. We can get it easily if we use ISOWEEKNUM. That is, if you want to get the week number of your date according to the ISO 8601 standard.

Want to know more about ISOWEEKNUM and how to use this function properly in excel? Read this Compute Expert tutorial until its last part!

Disclaimer: This post may contain affiliate links from which we earn commission from qualifying purchases/actions at no additional cost for you. Learn more







What is the ISOWEEKNUM Function in Excel?

ISOWEEKNUM is an excel function that helps you to get the ISO standard week number of a date.



ISOWEEKNUM Usability

You can use ISOWEEKNUM to get the week number of your date. The week number will be based on the ISO week-numbering year.

The ISO week-numbering year itself has two important rules we must pay attention to in relation to ISOWEEKNUM.
  • Each week starts on Monday
  • The first week of the year is the week that has the first Thursday

These points are crucial in determining the week number result you get from your date.



ISOWEEKNUM Result

The ISOWEEKNUM result is a number that represents the ISO week number of the date you input into it.



Excel Version from Which We Can Start Using ISOWEEKNUM

We can start using ISOWEEKNUM in excel 2013.



The Way to Write It and Its Input

Here is the general writing form of ISOWEEKNUM in excel.

= ISOWEEKNUM ( date )


You just need to input the date from which you want to get your week number to ISOWEEKNUM.

Learn Excel Dashboard Course



Example of Its Usage and Result

Here is an implementation example of ISOWEEKNUM in excel.

How to Use the ISOWEEKNUM Function in Excel: Usabilities, Examples, and Writing Steps - Screenshot of the ISOWEEKNUM Implementation Example

As you can see there, the way to get the week number of our date from ISOWEEKNUM is quite easy. Just input the date from which you want to get the week number and press enter. You will immediately get your result!



Writing Steps

Need guidance when you write your ISOWEEKNUM formula in excel? Read these ISOWEEKNUM writing steps below!

  1. Type an equal sign ( = ) in the cell where you want to put the week number of your date

    How to Use the ISOWEEKNUM Function in Excel: Usabilities, Examples, and Writing Steps - Screenshot of Step 1

  2. Type ISOWEEKNUM (can be with large and small letters) and an open bracket sign after =

    How to Use the ISOWEEKNUM Function in Excel: Usabilities, Examples, and Writing Steps - Screenshot of Step 2

  3. Input the date from which you want to get your week number. The week number you will get is based on the ISO week-numbering year

    How to Use the ISOWEEKNUM Function in Excel: Usabilities, Examples, and Writing Steps - Screenshot of Step 3

  4. Type a close bracket sign

    How to Use the ISOWEEKNUM Function in Excel: Usabilities, Examples, and Writing Steps - Screenshot of Step 4

  5. Press Enter
  6. Done!

    How to Use the ISOWEEKNUM Function in Excel: Usabilities, Examples, and Writing Steps - Screenshot of Step 6




ISOWEEKNUM vs WEEKNUM

There is another function in excel that can give you the week number of your date. That function is WEEKNUM.

Then, what is the difference between ISOWEEKNUM and WEEKNUM? Well, the difference is while you can only get an ISO 8601 week number from ISOWEEKNUM, WEEKNUM is more flexible. You can choose the week numbering standard you want to base on if you use the formula.

Learn Excel Dashboard Course


To understand the concept better, here is the general writing form of WEEKNUM in excel.

= WEEKNUM ( date , [ week_numbering_standard_code ] )


Besides inputting a date, you can also determine the week numbering standard you want to WEEKNUM. If you don’t input anything for that, WEEKNUM will have its week starts from Sunday. It will also have the first week of the year as the one which has the year’s first day (January 1).

Here are the week numbering standard code input options you can give to WEEKNUM.

Week Numbering Standard CodeWeek Starts on
1Sunday
2Monday
11Monday
12Tuesday
13Wednesday
14Thursday
15Friday
16Saturday
17Sunday
21Monday


All, except for code 21, have their first week of the year in the week of the year’s first day. Code 21 is for the ISO 8601 week numbering standard, the same basis as the one that ISOWEEKNUM uses. It starts each week on Monday and the year’s first week is the one which has the first Thursday.

Here is the implementation example of WEEKNUM with its comparison with ISOWEEKNUM.

How to Use the ISOWEEKNUM Function in Excel: Usabilities, Examples, and Writing Steps - Screenshot of the WEEKNUM Implementation Example and Its Comparison with ISOWEEKNUM

You can see here if we input 21 as the WEEKNUM second input, we should have a similar result to ISOWEEKNUM. We can have a different result, though, if we use other week numbering standard code in WEEKNUM. That is because WEEKNUM will then use a different week numbering standard than the ISOWEEKNUM.

So, whenever you want to get the week number of a date on ISO 8601 basis, use ISOWEEKNUM to be simpler. However, if you want another week’s numbering standard, use WEEKNUM instead.



Exercise

After you have understood how to use ISOWEEKNUM in excel, now let’s do an exercise to sharpen your understanding.

Download the exercise file and answer the questions below. Download the answer key file if you have done all the questions and want to check your answers. Or probably if you are confused about how to do the exercise and want to have a clue about it!

Link to the exercise file:
Download here

Questions

Use the excel ISOWEEKNUM function to answer all the questions below. Give the answers on the gray-colored cells in each appropriate row number.
  1. What is the week number that you get from the date on the left?
  2. What is the week number that you get from the date on the left?
  3. What is the number that you get if you subtract the week number no. 2 with the week number no.3?

Link to the answer key file:
Download here



Additional Note

The date you input to ISOWEEKNUM must be a date that Excel recognizes. If you input an invalid date to ISOWEEKNUM, you will get a #VALUE error.

Need be sure the date you write in excel is valid? You can use the DATE formula to write it.



Related tutorials you should learn too:



Want to Learn More About Excel?


Get updated excel info from Compute Expert by registering your email. It's free!





Want to Learn More About Excel?


Get updated excel info from Compute Expert by registering your email. It's free!




Follow our tutorial content also on


Excel Calculation

Sum in Excel

Subtraction in Excel

Multiplication in Excel

Division in Excel

Average in Excel



Excel Formula

VLOOKUP Function in Excel

IF Function in Excel

SUM Function in Excel

COUNTIFS Function in Excel

SUMIFS Function in Excel



Excel Tips and Trick

How to Print in Excel

Convert Number to Text in Excel

Excel Worksheet Definition

Excel Range Definition

Excel Shortcuts



Excel Products & Services Recommendation

Best Laptops for Excel

Best Tablets for Excel

Best Keyboards for Excel

Best Mouse for Excel

Best Monitors for Excel



Excel Consultation

About Us

Contact Us

Privacy Policy

Affiliate Disclosure

Terms & Condition



© 2022 Compute Expert