Please Note: This article is written for users of the following Microsoft Word versions: 2007, 2010, 2013, and 2016. If you are using an earlier version (Word 2003 or earlier), this tip may not work for you. For a version of this tip written specifically for earlier versions of Word, click here: Determining Differences Between Dates.

Determining Differences Between Dates

by Allen Wyatt
(last updated January 21, 2017)


When you are programming 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. (Yes, that's the year 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.

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:

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.

WordTips is your source for cost-effective Microsoft Word training. (Microsoft Word is the most popular word processing software in the world.) This tip (12380) applies to Microsoft Word 2007, 2010, 2013, and 2016. You can find a version of this tip for the older menu interface of Word here: Determining Differences Between Dates.

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. ...


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What is five more than 3?

2017-01-23 11:06:11

Alex: Note that the tip is about VBA programming (macros). The base date in VBA is, indeed, much different than the base date within Excel itself.

And, this is not a recent change.


2017-01-23 09:56:56

Alex Bayman

Interesting - I thought the base date was 1 January 1900. Is this a recent change by Microsoft?

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