This week number excel

Week Number in Excel (WEEKNUM)

Week Number (WEEKNUM) is a DATE function in Excel that gives us the week number for the given date in a date. It has two arguments: one which takes a date as an argument which can be a date or a serial number. The other argument is optional, which represents the day on which the week begins. The second argument is optional; however, the first argument is mandatory. The method to use this WEEKNUM function is as follows: =WEEKNUM(serial_number,[return_type]). If the return type is not provided, Sunday is considered one by default.

For example, suppose cell A1 has July 8, 2021, which falls on Thursday. On applying the WEEKNUM Excel function, it will return 28.

=WEEKNUM(A1) 

=28.

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Source: Week Number in Excel (wallstreetmojo.com)

Syntax

• serial_number: This is the date. Based on this date, we are trying to find the week number of the date. Excel treats DATE as a serial number.
• return_type: We need to mention the start of the weekday.

We have 10 different options to supply at the start of the week. Since this is an optional argument, we need not mandatorily supply the argument. However, if we leave this argument blank by default, the value will be 1, i.e., the start of the day of the week is Sunday.

The start of the year, Jan 01, will always be the first week of the year, and Dec 31 will always be the last week of the year, the 54th week.

How to Use the Week Number (WEEKNUM) Function in Excel?

Example #1 – Finding Week Number in Excel

Example #2 – Add the Word WEEK to the Week Number in Excel

We have seen how to return the week number of any supplied date. It will be cool to add the word “Week” before the week’s number, like in the image below.

It is where the advanced formatting technique in excelFormatting is a useful feature in Excel that allows you to change the appearance of the data in a worksheet. Formatting can be done in a variety of ways. For example, we can use the styles and format tab on the home tab to change the font of a cell or a table.read more comes into the picture. Follow the below steps to apply the above formatting.

• Step 1: Select all the result cells first.

• Step 2: Right-click on the selected cells and select “Format Cells.” You can directly press the shortcut key “Ctrl + 1.”

• Step 3: Now, we will see below format dialog box. Go to “Custom” first.

• Step 4: Enter the format code “Week” # in the Type: area.

• Step 5: Press “OK.” We will have results ready.

Instead of changing the formatting of the cells, we can also combine the word “Week” with the result cells. Refer to the image to apply the same.

Example #3 – Calculate Number of Weeks in excel between Two Dates

We have learned the technique of finding the week number of the supplied technique in Excel. But, how do you tell how many weeks are between two dates?

Assume you started the project on 15th Jan 2018, and you completed the project on 30th April 2018. How do you tell how many weeks you had taken to complete the project?

• Step 1: Firstly, find the difference between the two dates.

• Step 2: Now, divide the difference by 7. We have 7 days a week.

• Step 3: Press the “Enter” key to complete the formula. We have a result like this.

• Step 4: Change the format to “General” for accurate results.

Example #4 – Calculate the Number of Weeks in Fraction using Excel

Let us consider one more example to have a clear idea about finding the week’s number between two dates in Excel.

You are going on a business trip from 15th Feb 2018. After all the duties are completed, you are coming back on 30th Jun 2018. Your business head decided to pay you the money weekly.

Now, you must tell me how many weeks you are going on a business trip. Let us apply the same formula we have used in the previous example.

Find the difference between two dates.

Now, divide the difference by 7. So we have 7 days a week.

We have a result like this.

Let us change the format of the resulting cell to fractions.

So, we have the number of weeks in fractions now.

Things to Remember

• By default, the start of the week in Excel is SUNDAY.
• We must supply the return type correctly if you want to start with a different week.
• If the date is not in the correct format, we may get #VALUE! Error.

Recommended Articles

This article is a guide to WEEKNUM in Excel. We discuss finding week numbers in Excel using the WEEKNUM function, practical examples, and a downloadable Excel template. You may learn more about Excel from the following articles: –

• Weekday in VBAWeekday in VBA is a date and time function to identify the weekday of a given date provided as an input. This function returns an integer value from 1 to 7 range. There is an optional argument provided to this function which is the first day of the week.read more
• DATEDIF Function in Excel
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Excel Week Numbers (Table of Contents)

• Week Numbers in Excel
• How to use Week Number (WEEKNUM) Function in Excel?

Week Numbers in Excel

It is quite a painful job to find out week number for a specific date manually. What if I tell you, excel does this job of finding week number for you? Yes, you heard it right! Excel can calculate the week number for a specific date or set of dates and give a week number for you with the help of the WEEKNUM function. Yes, only one specific function (less confusion, right?). However, this one function itself could be confusing some of the times. Let’s go through and see how it works and helps us find out the week number in excel.

Syntax for WEEKNUM Function in;

The syntax for the excel WEEKNUM function, which outputs week number from a given date value, is as below:

Where,

• serial_number: is a date value for which you want to calculate the week number. It can be a reference of the cell which is containing your date value.
• return_type: is a number which can let excel know on which day the week has started. This is an optional but really very useful argument which can be confusing at the same time.

When the above formula is entered on a date argument, Excel finds out the week number for that date and returns a number from 1 to 52 (as there are 52 weeks in a year).

How to use Week Number (WEEKNUM) Function in Excel?

Let’s understand how to use the Week Number Function in Excel by using some examples.

You can download this Week Numbers Excel Template here – Week Numbers Excel Template

Week Numbers in Excel – Example #1

Simple WEEKNUM Function in Excel (Without [return_type]):

As you might have paid attention above, return_type is an optional argument and can be omitted. If omitted, Excel considers that the first week of the year starts on January 1^st, and the last week (i.e. week number 52) will be December 31^st.

What if you ignore the return_type? Is it OK? Will Excel still count the week number for a date?

The answer to all these questions is affirmative. Let’s see an example and have a practical understanding of the same.

Suppose we have data as shown in the image below, which has different dates in each cell.

Put the formula =WEEKNUM(A2) in cell B2 and hit Enter. 

Excel will return a week value for the date in cell A2. See the screenshot below for a better understanding:

Since we have omitted the return_type, Excel considered that the week starts from January 1^st and it’s a week from Sunday to Sunday (Though 1^st January 2017 was actually a Sunday, It becomes confusing when the 1^st day of the year does not fall on Sunday).

Let’s drag the formula for all the cells and see the values for the week number corresponding to every date value.

See the below example for your reference:

This was pretty simple till here, right?

Week Numbers in Excel – Example #2

WEEKNUM Function with return_type:

In the previous section, we ran the function without providing the return_type. Which means, by default, the week starts on 1^st January and assumes that it is Sunday.

But which may not be the case of our interest always. Our week might start on Monday, Tuesday etc., at the start of the year.

Therefore, the return_type is there.

return_type has the following list of values supported, and you can also see those when you use it under the WEEKNUM formula.

All the above values for argument are used under the WEEKNUM function.

Let’s play around with some of the return_type values and see the magic.

Suppose you wanted your week to be starting from Monday, then give return_type as 2 under the WEEKNUM formula and see if any change in week numbers.

See the below screenshot for your reference.

As you can see through highlighted cells, the week number values have changed when we have used return_type as Monday (i.e. 2). It happened because 1^st January 2017 is falling on Sunday. So ideally week should have started from the date. But as we have provided the return_type as Monday, Excel considers that the week is about to start from the first Monday of 2017 (which is 2^nd January 2017), and hence there is an increase in week value.

Week Numbers in Excel – Example #3

ISOWEEKNUM function:

ISOWEEKNUM function allows you to find out the ISO week number of the week for a particular date. This function is as per the ISO standards, which says the week starts on Monday, and the week containing the first Thursday is considered as the first week of the year. This function will give you a week value from 1 to 52, specifying on which week the date value falls.

The syntax for ISO week is as above, where the argument named to date is required for the function to calculate the week number as per the ISO standards.

Let’s see some examples of this.

Suppose we have a date 1^st January 2017, which is Sunday. The value the ISOWEEKNUM function gives is 52, which denotes the last week of 2016. Because the week starts on Monday under ISOWEEKNUM and the date is falling on Sunday.

As 2^nd January 2017 falls on Monday, ISOWEEKNUM gives week value as one.

Now suppose a date 1^st January 2015, which is a Thursday. ISOWEEKNUM considering it as the first week of the year, and the same you can see under output.

So, these were some of the examples on week numbers. I hope this article helps you get in the concept right. I will suggest having some more practice with different return_type values under the function to gets hands-on with it.

Things to Remember

• return_type can be omitted in excel. However, omitting leads to the start of the week from 1^st January of the year, and excel considers that it’s a Sunday.
• return_type “21” can only be used under the ISOWEEK numbering system.
• ISOWEEKNUM function only requires one argument called date. It should be the cell which contains the actual date for which you wanted to calculate the week number as per ISO standards.
• General WEEKNUM functions provide week numbers from 1 to 54. However, the ISOWEEKNUM function provides week numbers only from 1 to 52.

Recommended Articles

This has been a guide to Week Numbers in Excel. Here we discussed How to find week numbers and How to use the WEEKNUM and ISOWEEKNUM Function in Excel, along with practical examples and a downloadable excel template. You can also go through our other suggested articles –

1. Month Function in excel
2. Excel Formula for Weekday
3. WEEKDAY Function Excel
4. Insert Calendar In Excel