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

Deciphering a Coded Date

Written by Allen Wyatt (last updated August 15, 2022)
This tip applies to Excel 2007, 2010, 2013, and 2016


3

Luis receives information in which dates are coded such that years, months, and days are replaced with a single character each. For each field, the numbers 1 to 9 are used and after that letters, from a=10, b=11, ... v=31. For example, the date code 'bc2' means b=11 (the year 2011), c=12 (the month), and day=2. Luis wonders if a function can be devised to replace the coded date with a common date format, such as dd/mm/yyyy.

There are actually several ways you could go about solving this problem. One way is to set up "equivalence tables" within a worksheet, where the left column includes a code character and the right indicates the numeric value that is associated with that character. You could then fashion a formula that uses VLOOKUP to find the values and convert the results into a date.

As an example, create your equivalence table in some unused cells to the right of your data. In my case, I put the table in columns P and Q. In column P I put the code characters, 1 through 9 and a through z. (Make sure you precede the digits 1 through 9 with an apostrophe so they are stored as text rather than as numbers.) In column Q I put the numbers 1 through 35. This entire range (P1:Q35) I then gave a name of DateTable. Here is the formula, then, that will return a decoded date for a coded date stored in cell A1:

=DATE(2000+VLOOKUP(LEFT(A1,1),DateTable,2,0),
VLOOKUP(MID(A1,2,1),DateTable,2,0),VLOOKUP(RIGHT(A1,1),
DateTable,2,0))

Remember that this is a single, continuous formula. Another technique is to bypass the equivalence tables altogether and instead use a formula to do the conversion. The following is an example that will decode a date in cell A1:

=DATE(2000+FIND(LEFT(A1,1),"123456789abcdefghijklmnopqrstuvwxyz"),
FIND(MID(A1,2,1),"123456789abc"),FIND(MID(A1,3,1),
"123456789abcdefghijklmnopqrstuv"))

This formula uses the FIND function to translate from the code character to a value, and then these values are used in the DATE function to return the desired date. Another possible formula relies, instead, on character code values to create the date:

=DATE(2000+CODE(MID(A1,1,1))-87+(CODE(MID(A1,1,1))<58)*39,CODE(MID(A1,2,1))-87+(CODE(MID(A1,2,1))<58)*39,CODE(MID(A1,3,1))-87+(CODE(MID(A1,3,1))<58)*39)

Finally, you could create a user-defined function to return the decoded date. The following is just a simple example; it looks at each character and converts it to a numeric value that is then used with the DateSerial function to create an Excel date serial number:

Function DecodeDate(datecode As String)
    Const X = "123456789abcdefghijklmnopqrstuvwxyz"
    Dim D As Integer
    Dim M As Integer
    Dim Y As Integer

    Application.Volatile
    D = InStr(X, Right(datecode, 1))
    M = InStr(X, Mid(datecode, 2, 1))
    Y = 2000 + InStr(X, Left(datecode, 1))
    DecodeDate = DateSerial(Y, M, D)
End Function

It should be pointed out, as well, that regardless of the approach you use, there is an inherent flaw in your date codes. The year uses the code values 1 through 9 and a through z. This means that the date code can be one of 35 possible values. When added to the year 2000 (the base year for how you described the code), that means that the maximum year value that can be coded is 2035. Any date after that year will not work with this coding.

Note:

If you would like to know how to use the macros described on this page (or on any other page on the ExcelTips sites), I've prepared a special page that includes helpful information. Click here to open that special page in a new browser tab.

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (12423) applies to Microsoft Excel 2007, 2010, 2013, and 2016. You can find a version of this tip for the older menu interface of Excel here: Deciphering a Coded Date.

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

Jumping between Columns

Need to jump from one column to another on a page? You can use the handy shortcut keys described in this tip.

Discover More

Using Mandatory Form Fields

When using form fields to gather information from users of your documents, you may want to make sure that some of the ...

Discover More

Saving a Workbook in a Macro

Does your macro need to make sure that the workbook being processed is saved to disk? You can add the saving capability ...

Discover More

Comprehensive VBA Guide Visual Basic for Applications (VBA) is the language used for writing macros in all Office programs. This complete guide shows both professionals and novices how to master VBA in order to customize the entire Office suite for their needs. Check out Mastering VBA for Office 2010 today!

More ExcelTips (ribbon)

Calculating Future Workdays

Need to calculate the date that is a certain number of workdays in the future? You can do so using a couple of different ...

Discover More

Using a Text Function with a Date/Time Returns an Error

If you use a text function with a date or time, you'll get an error. To understand why this occurs (and how to get around ...

Discover More

Parsing Non-Standard Date Formats

When you load data into Excel that was created in other programs, the formatting used for some types of data (such as ...

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 8 + 8?

2022-08-15 16:42:10

Philip

This rather sounds like a task for which Power Query would be ideal. Although my first question to the provider of the data would be why such a coding practice for dates would even be used in the first place (I havn’t come across any use cases yet in my 35 years of Excel)


2022-08-15 11:13:59

Rick Rothstein

Here is another formula that will do the conversion directly...

=DATE(2000+HEX2DEC(LEFT(A1)),HEX2DEC(MID(A1,2,1)),CODE(RIGHT(A1))+39*ISNUMBER(0+RIGHT(A1))-87)


2022-08-15 04:41:53

Jean-Pierre Degroote

With the use of the DECIMAL function:

=DATEVALUE(2000+DECIMAL(MID(A3;1;1);36)&"/"&DECIMAL(MID(A3;2;1);36)&"/"&DECIMAL(MID(A3;3;1);36))

(Excel for Microsoft 365 Excel for Microsoft 365 for Mac Excel for the web Excel 2021 Excel 2021 for Mac Excel 2019 Excel 2019 for Mac Excel 2016 Excel 2016 for Mac Excel 2013 Excel for Mac 2011)


This Site

Got a version of Excel that uses the ribbon interface (Excel 2007 or later)? This site is for you! If you use an earlier version of Excel, visit our ExcelTips site focusing on the menu 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.