ISOWEEKNUM Excel Formula
In this tutorial, you will learn the use of the ISOWEEKNUM excel formula. Excel ISOWEEKNUM function is useful to get the week number of a date in its year.
Why do We Need to Learn Excel ISOWEEKNUM Function?
In the data processing on a spreadsheet, sometimes we need to know the week number of a date in its year. It is needed so we can process the week number data for further analysis such as data entries groupings based on a period or calculation operation by using the number. The data for this need is quite hard if we want to get it manually especially if it is needed to be done on many dates in our spreadsheet.
As an example of the need for the number in our work, let’s say we want to group product sales based on its weekly period. It might be needed so we can see the sales development week by week and determine whether something that we do between the periods such as a promotion or the modification of the product content gives a positive or negative effect on the sales performance. Often the sales data to be analyzed is much looking at its amount. If we do the week number identification for each of the sales dates in the spreadsheet manually, then it will waste much time that can be used to do further analysis of the sales performance.
Because of this, to make the identification to all dates data easier, then you can use the ISOWEEKNUM excel formula. Excel ISOWEEKNUM function is useful to get the week number of a date in its year period. It is useful to be learned and understood if you often do data processing and grouping based on a particular period.
What is ISOWEEKNUM Excel Formula?
ISOWEEKNUM excel formula is a formula with the usage objective to get the week number of a date in its year. The determination uses ISO standard where every week begins on Monday and number 1 will be got from the earliest week of a year that has Thursday in it.
Generally, the description of this formula’s input can be explained as follows:
=ISOWEEKNUM(date)
Note:
date = date to be processed by the formula
How to Use Excel ISOWEEKNUM Function?
The following will explain the stepbystep use of excel ISOWEEKNUM function. Excel ISOWEEKNUM function needs just one input which is the date that you want to process to get its week number.
Using ISOWEEKNUM Excel Formula

Type equal sign ( = ) in the cell where you want to put the result in

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

Input the date data / cell coordinate where it is located after open bracket sign

Type close bracket sign
 Press Enter

The process is done!
Exercise
After you have understood how to use ISOWEEKNUM excel formula, now is the time you 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 if you are confused about how to do the exercise!
Link to download the exercise file:
Download here
Questions
Use excel ISOWEEKNUM function to answer all the questions below on the graycolored cells in each appropriate row number: What is the digit that you get from the data on the left by using the function?
 What is the digit that you get from the data on the left?
 What is the result if the digit that you get from the date no. 3 is subtracted by the digit from the date no. 2?
Link to download the answer key file:
Download here
Additional Notes
The number that is resulted in this formula is 154, in line with the maximum amount of weeks in a year.