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: Determining Differences Between Dates.
Written by Allen Wyatt (last updated October 29, 2022)
This tip applies to Excel 97, 2000, 2002, and 2003
When you are programming Excel macros, you should know that dates are stored internally, within variables, as serial numbers. The serial number represents the number of days elapsed since a starting "base date," specifically since 1 January 100. This means that you can perform math with the serial numbers, if desired. You can, for instance, find the number of days between two dates by simply subtracting the dates from each other.
Note that the starting date above is not a typo; in macros the calculations are from a much earlier base date than they are in a worksheet. (Worksheets use either 1900 or 1904 as their base date, depending on how you've configured Excel.) This means that macros can work with a much wider range of dates than can be done in worksheets.
If you want to get fancier in your date calculations, you can use the DateDiff function. This function allows you, for instance, to determine the number of weeks or months between two dates. In order to use the function to find this type of information, you would do as follows:
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:
iNumWeeks = DateDiff("ww", dFirstDate, dSecondDate)
iNumMonths = DateDiff("m", dFirstDate, dSecondDate)
The first line determines the number of weeks between the two dates, and the second determines the number of months between them.
Note:
ExcelTips is your source for cost-effective Microsoft Excel training. This tip (2535) 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: Determining Differences Between Dates.
Program Successfully in Excel! This guide will provide you with all the information you need to automate any task in Excel and save time and effort. Learn how to extend Excel's functionality with VBA to create solutions not possible with the standard features. Includes latest information for Excel 2024 and Microsoft 365. Check out Mastering Excel VBA Programming today!
Want to know when a workbook was last modified? Want to put that date within the header of your worksheet? Here's how to ...
Discover MoreWant to add a bunch of blank rows to a your data and have those rows interspersed among your existing rows? Here's a ...
Discover MoreWhen you use a macro to do file operations, it works (by default) within the current directory. If you want to know which ...
Discover MoreFREE SERVICE: Get tips like this every week in ExcelTips, a free productivity newsletter. Enter your address and click "Subscribe."
There are currently no comments for this tip. (Be the first to leave your comment—just use the simple form above!)
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.
FREE SERVICE: Get tips like this every week in ExcelTips, a free productivity newsletter. Enter your address and click "Subscribe."
Copyright © 2026 Sharon Parq Associates, Inc.
Comments