Please Note: This article is written for users of the following Microsoft Excel versions: 97, 2000, 2002, and 2003. If you are using a later version (Excel 2007 or later), this tip may not work for you. For a version of this tip written specifically for later versions of Excel, click here: Using the WEEKNUM Function.

Using the WEEKNUM Function

Written by Allen Wyatt (last updated July 10, 2021)
This tip applies to Excel 97, 2000, 2002, and 2003


One of the functions provided in the Analysis ToolPak is WEEKNUM. This function is used, oddly enough, to return the week number represented by a particular date. You use the function in this way:

=WEEKNUM(A5,1)

In this instance, A5 contains a date serial number, and the value 1 indicates that WEEKNUM should assume that all weeks start on a Sunday. If you prefer your weeks to begin on Mondays, then you can use the value 2 instead.

You should realize that WEEKNUM always considers the first day of any given year to be in the first week of the year. Thus, it is possible for the above formula to return up to 54 weeks in a year. How can this be? Let's use the year 2011 as an example. In 2011 January 1 falls on a Saturday. As far as WEEKNUM is concerned, this is in the first week of the year. Now, January 2 for that year falls on a Sunday. Since WEEKNUM believes that every Sunday starts a new week, the second day of the week is considered in the second week of the year.

This is fine, until you get to the end of the year. The fifty-second week of 2011 ends (according to WEEKNUM) on December 24, and the fifty-third week begins on December 25 (a Sunday).

An even more interesting scenario is when the year begins on a Saturday and the year is a leap year. This happened in the year 2000. In that instance, the fifty-third week began on December 24, and the fifty-fourth week began on December 31.

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (2326) applies to Microsoft Excel 97, 2000, 2002, and 2003. You can find a version of this tip for the ribbon interface of Excel (Excel 2007 and later) here: Using the WEEKNUM Function.

Author Bio

Allen Wyatt

With more than 50 non-fiction books and numerous magazine articles to his credit, Allen Wyatt is an internationally recognized author. He is president of Sharon Parq Associates, a computer and publishing services company. ...

MORE FROM ALLEN

Printing Unwanted Blank Envelopes

When you try to print an envelope in Word, it can be vexing if the envelope always goes through the printer and remains ...

Discover More

Using the EOMONTH Function

If you need to determine the date of the last day in a month, it's hard to beat the flexibility of the EOMONTH function. ...

Discover More

Ordering Search and Replace

The wildcard searching available in Word is very powerful. Here's how you can use ordering in your search efforts to make ...

Discover More

Create Custom Apps with VBA! Discover how to extend the capabilities of Office 2013 (Word, Excel, PowerPoint, Outlook, and Access) with VBA programming, using it for writing macros, automating Office applications, and creating custom applications. Check out Mastering VBA for Office 2013 today!

More ExcelTips (menu)

Numbers in Base 12

Different professions use numbers in entirely unique ways. You may need to come up with a number that represents the ...

Discover More

Converting Strings to Numbers

When working with data in a macro, there are two broad categories you can manipulate: numbers and text. Sometimes you ...

Discover More

Calculating Fractions of Years

When working with dates and the relationship between dates, Excel provides a variety of worksheet functions that may ...

Discover More
Subscribe

FREE SERVICE: Get tips like this every week in ExcelTips, a free productivity newsletter. Enter your address and click "Subscribe."

View most recent newsletter.

Comments

If you would like to add an image to your comment (not an avatar, but an image to help in making the point of your comment), include the characters [{fig}] (all 7 characters, in the sequence shown) in your comment text. You’ll be prompted to upload your image when you submit the comment. Maximum image size is 6Mpixels. Images larger than 600px wide or 1000px tall will be reduced. Up to three images may be included in a comment. All images are subject to review. Commenting privileges may be curtailed if inappropriate images are posted.

What is 3 + 5?

There are currently no comments for this tip. (Be the first to leave your comment—just use the simple form above!)


This Site

Got a version of Excel that uses the menu interface (Excel 97, Excel 2000, Excel 2002, or Excel 2003)? This site is for you! If you use a later version of Excel, visit our ExcelTips site focusing on the ribbon interface.

Newest Tips
Subscribe

FREE SERVICE: Get tips like this every week in ExcelTips, a free productivity newsletter. Enter your address and click "Subscribe."

(Your e-mail address is not shared with anyone, ever.)

View the most recent newsletter.