Conditionally Formatting for a Pattern

by Allen Wyatt
(last updated July 3, 2019)


Kim has a column of data used to contain a location code. This code consists of a single letter followed by two digits, such as A03 or B12. Kim would like to conditionally format the column so that anything entered into the column that doesn't use this pattern is highlighted in some way.

There are many ways that this problem can be approached. Each approach depends on developing a formula that can be used within a conditional formatting rule to return either True or False and trigger the conditional format. (This tip won't go into how to create a conditional formatting rule, but will instead focus on the various formulas that can be used in the rule. How you create conditional formatting rules is covered in other ExcelTips.)

Whatever formula is put together has to test three things:

  • There are exactly three characters in the string.
  • The first character is a letter.
  • The second and third characters are digits.

Finding out if the text in a cell has only three characters is rather easy; you can use the LEN function to do it:


Finding out if the first character is a letter is also rather easy. In fact there are a couple of ways it can be done. Any of the following will return True if the first character is a letter:


These check to make sure that only an uppercase letter is in the first position. If you want to also accept lowercase letters, then you can use a variation of the second test:


If both upper- and lowercase letters are acceptable (along with virtually any other symbol), then you might consider using the following test:


Here are a couple of ways you can apply the third test-whether the second and third characters are digits:


Note that these approaches treat the last two characters together. This means that "1", "11," and "111" would all pass the test—they successfully check out as numbers. If your formula were checking only the last two digits, this could be a problem, but the fact that you will also include the first check (for the overall length of the string in the cell and that it must be 3), then it doesn't present a problem at all.

The trick, now, is to combine your approach-of-choice for each of the three tests into a single formula. This can be done using the AND function. I'll just pick the shortest from each of the tests and combine them in this way:

=AND(LEN(A1)=3, AND(LEFT(A1,1)>="A",LEFT(A1,1)<="Z"), =ISNUMBER(--RIGHT(A1,2)))

As written, this formula returns True if all the tests are passed, which means that the cell contains a location code with a valid pattern. This would work great as a conditional format if Kim were to format the column as a color (say, green) and then use the conditional format to remove the green color. This may seem backward, and you may actually only want to apply a format if the pattern isn't met. If that is the case, then simply encase the formula in a NOT function to reverse the True/False that is returned:

=NOT(AND(LEN(A1)=3, AND(LEFT(A1,1)>="A",LEFT(A1,1)<="Z"), =ISNUMBER(--RIGHT(A1,2))))

As you can tell, using a formula like this can be a bit tricky. You could, if you prefer, created a UDF (user-defined function) that would make the conditional formatting rule a bit shorter. The following macro is a good way to go:

Function IsBadPattern(sCell As String) As Boolean
    IsBadPattern = Not(sCell Like "[A-Z][0-9][0-9]")
End Function

To use the UDF in your conditional formatting rule, all you need to do is use the following formula:


The result of the UDF will be TRUE if the string in the referenced cell doesn't match the pattern you wanted. As written, it won't allow for the use of lowercase letters in the first character position. If you need to allow lowercase letters, you don't need to change the UDF. Instead, change the formula to the following:


ExcelTips is your source for cost-effective Microsoft Excel training. This tip (9976) applies to Microsoft Excel 2007, 2010, and 2013.

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. ...


Precisely Adjusting Tab Stops

When you need to be very specific about where a tab stop is located, you'll want to become familiar with the Tabs dialog ...

Discover More

Getting Rid of Numbered Columns

Excel normally refers to columns as A, B, C, etc. It also has a referencing format that allows columns to be referred to ...

Discover More

Adding Common Line Spacing Options

Sometimes the options presented by Word's tools don't exactly meet our formatting needs. Rather than changing the tools ...

Discover More

Professional Development Guidance! Four world-class developers offer start-to-finish guidance for building powerful, robust, and secure applications with Excel. The authors show how to consistently make the right design decisions and make the most of Excel's powerful features. Check out Professional Excel Development today!

More ExcelTips (ribbon)

Conditionally Highlighting Cells Containing Formulas

Excel's conditional formatting feature allows you to create formats that are based on a wide variety of criteria. If you ...

Discover More

Finding Cells that Use Conditional Formatting

Conditional Formatting is a great boon to effectively displaying the information in your worksheets. If you want to ...

Discover More

Detecting Errors in Conditional Formatting Formulas

If an error exists in a formula tucked inside a conditional format, you may never know it is there. There are ways to ...

Discover More

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

View most recent newsletter.


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}] 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 0 + 4?

2015-05-11 07:36:37


There's a typo in two of the formulas provided. The equal-sign before ISNUMBER should be removed - for example,
=AND(LEN(A1)=3, AND(LEFT(A1,1)>="A",LEFT(A1,1)<="Z"), ISNUMBER(--RIGHT(A1,2)))

2015-05-09 15:47:55



using a UDF obviously has a very distinct disadvantage: it requires the user to allow macros/scripting.

2015-05-09 13:44:01

John Hamm

It is not necessary to specify the leftmost character when applying the CODE function. CODE("hello") yields the same result as CODE("h").

The second and third characters should be tested independently. When they are tested together, entries such as B-4, B+4 and B.4 pass as conforming to the pattern.

I prefer applying a custom format to only those values that do not match the pattern. Here is a formula that is TRUE when either of the second two characters is not a digit: =ISERROR(MID(A1,2,1)+RIGHT(A1,1))

2015-05-09 13:07:23

Willy Vanhaelen

Instead of combining the 3 tests you can enter them separatly as 3 consecutive rules.


Leave the first two with "No Format Set" and check "Stop If True".
For the third rule set the format of your choice.

The third formula is not case sensitive so UPPER() is not needed and
give the same result.

2015-05-09 07:51:42

Mohammed Hasil

Wow! Nice ideas!!! Thanks.

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

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.