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Identifying Duplicate Values in an Excel List, Part 2

Aug 23rd 2013
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In a previous article I explained how you can use Conditional Formatting in Excel 2007 and later to highlight duplicate values with just a couple of mouse-clicks. Although easy to implement, this technique identifies all instances of a duplicate value. A reader then asked how to format only the second and any subsequent instances. In this article I'll explain how, along with instructions on identifying duplicate values in Excel 2003 and earlier.

Figure 1: Conditional Formatting can identify the second and subsequent instances of duplicate values.

Let's say that we have a list of names, such as shown in Figure 1. Our goal is to highlight the second and any subsequent times that a name appears more than once on a list. To do so, we'll select the names, and then carry out these steps:

  • Excel 2007 and later: Choose Conditional Formatting from the Home tab, followed by New Rule, and then Use a Formula to Determine Which Cells to Format.
  • Excel 2003 and earlier: Choose Format, Conditional Formatting, and then change Cell Value Is to Formula Is.

In all versions of Excel, enter the following formula:

=COUNTIF($A$1:A1,A1)>1

Click the Format button, and then choose a color from the Fill tab in Excel 2007 and later, or the Patterns tab in Excel 2003 and earlier. Click OK twice to close the conditional formatting dialog boxes. Your resulting list should look like Figure 1.

In Excel 2003 you can use this formula to recreate the functionality discussed in my previous article:

=COUNTIF(A:A,A1)>1

With regard to the formulas, the COUNTIF function counts how many times an item appears in a given range. For the first formula, I'm using an expanding range anchored by $A$1. On subsequent rows A1 (without the dollar signs) becomes A2, A3, A4, and so on. This is how we're able to identify just the second instance and beyond because the formula will only return TRUE for the second instance and beyond.

For the second formula, I'm counting if an item appears more than once anywhere in the column. This means that all instances, including the first instance, of a duplicate item will be formatted with the color of your choice.

In the previous article, I describe how you can filter by color in Excel 2007 and later. Although this isn't possible in Excel 2003, you can place the COUNTIF functions shown above in a column adjacent to your data and then choose Data, Filter, and then AutoFilter to turn on the filtering arrows. Choose Custom from the drop-down arrow in the column that contains the COUNTIF formula you added, select Is Greater Than, enter 1, and then click OK.

Replies (8)

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By John Galt
Jun 26th 2015 01:11

not helpful. an example formula and result would have helped.

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Replying to SanjayDarji:
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By David Ringstrom
Jun 26th 2015 01:11

Thank you for sharing your thoughts. I'm puzzled, though because I explained this formula =COUNTIF($A$1:A1,A1)>1 and the figure shows the result.

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Replying to juliagumm:
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By Probuddha
Jun 26th 2015 01:11

Very helpful, thanks! I am wondering what to use if I want a formula to ignore the second instance of a value, but highlight the first?

Also what would this do - =COUNTIF($A$1:A2,A2)>1 ?

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Replying to juliagumm:
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By ExcelDutchess
Jun 26th 2015 01:12

How could I create an automatic list of duplicates in an Excel Column so it would show: Lucas, Annabelle, Roger ?

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By Eassplus
Jun 26th 2015 01:11

Good day,
The example is helpful for me, but I have a Question, is there any chance to see the first instance just after enter de duplicate one? Because I have a lot of data in the same column. I have for example Surname and First name in A and B column but I want to see the Surname of the person when I enter a dupliclate First Name, in this example is easy to see because there are just a few data but is difficult to see it when is huge.

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By Dracula
Jun 26th 2015 01:12

How do you sort the result by color?

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By Striker
May 19th 2016 08:24

I copied the formula exactly and even tried using the exact data you had entered in the sample and absolutely nothing happened. How could that be?

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By anas447
Sep 13th 2017 09:14

Hi David,

i have a list of 19-digit-barcodes. Checking the duplication using conditional formatting is not working as it contains 19 digits.

Could you please give us a solution for this?

Thanks

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