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If you work regularly in spreadsheets, transferring various data from one cell to another, you have probably ended up with duplicate data across columns and/or rows. If your cells contain formulae, then it is also likely that this duplicate content has negatively affected your calculations. As a result, your data is no longer accurate, and it can become extremely time-consuming to manually highlight and remove each duplicate value.

This article will explain how to highlight duplicates in Google Sheets using the built-in conditional formatting feature as well as the =UNIQUE formula. You’ll then learn how to safely remove duplicates from any range in your dataset, whether they appear in one or two columns.

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How to find duplicates in Google Sheets in one column?

The quickest way to identify duplicates in Google Sheets is to color highlight them. You can perform a search for duplicates in one or two columns by using the Conditional Formatting feature; this will allow you to color format the cell or the text of the duplicate content. Let’s start by finding duplicates in one column.

  1. 1. Open your Google Sheets and select the column where you want to perform the search for duplicates. Don’t forget that your columns need to be named in order for this feature to work. Here, I’ll select Column A to find possible duplicate values of names.
How to Highlight Duplicates in Google Sheets Select column
How to Highlight Duplicates in Google Sheets - Select column
  1. 2. Go to Format > Conditional Formatting. The “Conditional Formatting” will open to the right-hand side of your screen.
How to Highlight Duplicates in Google Sheets Conditional formatting
How to Highlight Duplicates in Google Sheets - Conditional formatting
  1. 3. Check that the cell range shown corresponds to the column where you want to find duplicates. Then in the “Format cells if” drop-down list, select “Custom formula is”. A new field should now appear below.
How to Highlight Duplicates in Google Sheets Custom formula
How to Highlight Duplicates in Google Sheets - Custom formula
  1. 4. Enter the following formula in the new field, including the column range you selected previously. Here, I will enter =COUNTIF(A:A,A1)>1
How to Highlight Duplicates in Google Sheets COUNTIF formula
How to Highlight Duplicates in Google Sheets - COUNTIF formula
  1. 5. In “Formatting style” select a filling color for the duplicate cells. In this example, I will select “Red”.
How to Highlight Duplicates in Google Sheets Formatting style
How to Highlight Duplicates in Google Sheets - Formatting style
  1. 6. Another way to format the duplicate cell is to change the color of the text color; select the text color icon (A) in the menu bar. In this example, I will select “Red”.
How to Highlight Duplicates in Google Sheets Text color
How to Highlight Duplicates in Google Sheets - Text color
  1. 7. To apply the conditional formatting, click “Done”. It should now highlight all duplicates using your formatting.
How to Highlight Duplicates in Google Sheets Done
How to Highlight Duplicates in Google Sheets - Done

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As you can see above, the Conditional Formatting feature has successfully highlighted duplicate values in one column. Let’s now apply this same highlighting method to duplicate values in two columns.

How to find duplicates in Google Sheets in two columns?

Finding duplicates in Google Sheets in two columns is an almost identical process; the only difference is in the first step, where you need to select a larger range to include a second or third column. This is especially useful when your dataset is too large for you to remember where duplicates may have occurred. We recommend selecting the whole sheet. This is how you can find duplicates by applying conditional formatting to two columns.

  1. 1. Select the columns where you want to perform the search for duplicates. Here, I’ll select Column A and B to find possible duplicate values for both first names and last names.
How to Highlight Duplicates in Google Sheets Select columns
How to Highlight Duplicates in Google Sheets - Select columns
  1. 2. Go to Format > Conditional Formatting. The “Conditional Formatting” will open to the right.
How to Highlight Duplicates in Google Sheets Conditional formatting 2
How to Highlight Duplicates in Google Sheets - Conditional formatting
  1. 3. Check that the cell range shown corresponds to the two columns. Then in the “Format cells if” drop-down list, select “Custom formula is”. A new field should now appear below.
How to Highlight Duplicates in Google Sheets Custom formula is
How to Highlight Duplicates in Google Sheets - Custom formula is
  1. 4. Enter the same formula as before, including the range you selected. Here, I will enter =COUNTIF(A:B,A1)>1. As you can see, it’s almost the same formula as the previous example. Simply change the data range of the first parameter to the range of columns you want to check.
How to Highlight Duplicates in Google Sheets COUNTIF formula 2
How to Highlight Duplicates in Google Sheets - COUNTIF formula
  1. 5. In “Formatting style” select a fill color for the duplicate cells or font color. In this example, I will select a fill color in “Red”.
How to Highlight Duplicates in Google Sheets Fill in red
How to Highlight Duplicates in Google Sheets - Fill in red

To apply the formatting, click “Done”. All duplicates are now highlighted in the color you selected.

Now that you’ve seen how to highlight duplicates in one or various columns using the Conditional Formatting feature in Google Sheets, let’s ‌look at how you can achieve the same using the =UNIQUE formula.

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How to highlight duplicates in Google Sheets using a formula?

In the previous section, we showed you how to use the Conditional Formatting built-in feature combined with the =COUNTIF formula. However, you can use the =UNIQUE formula directly in your Google Sheets file to find and highlight duplicates in your worksheet.

  1. 1. Open your Google Sheets and type in “=UNIQUE” into an empty cell next to your data. You will see how Google Sheets prompts the full formula.
How to Highlight Duplicates in Google Sheets Enter UNIQUE
How to Highlight Duplicates in Google Sheets - Enter UNIQUE
  1. 2. You can complete the formula by clicking the letter at the top of the column you want to find duplicates in. Google Sheets will also include the column range for you. Here, I only want to find duplicates in Column A, so my completed formula looks like this: =UNIQUE(A:A).
How to Highlight Duplicates in Google Sheets Select column 2
How to Highlight Duplicates in Google Sheets - Select column
  1. 3. Press “Enter” to apply the formula. It will fill your column with only the unique values in your data range, skipping any duplicates. As you can see, this column has skipped the duplicate data in rows 12 and 13.
How to Highlight Duplicates in Google Sheets Enter
How to Highlight Duplicates in Google Sheets - Enter

You can also apply this formula to entire duplicate rows. Simply change the formula to include row numbers, rather than column letters. For example, to find duplicate rows in my data, I simply type in the following formula: =UNIQUE(2:17). As you can see below, the formula returns only the unique rows of data - it has skipped rows 12 and 13.

How to Highlight Duplicates in Google Sheets Unique rows
How to Highlight Duplicates in Google Sheets - Unique rows

As the formula will return entire values, adding them directly next to your dataset may cause an error message to appear. Instead, we recommend adding the formula directly below your dataset (as shown in the example above), as this will allow the UNIQUE formula to provide a full list of all your unique rows.

Now that we know the two main ways to highlight duplicates in Google Sheets, let’s see how we can quickly remove them.

How to remove duplicates in Google Sheets?

Once you have found and highlighted duplicates in one or two columns, a row, or an entire worksheet, you can easily remove them using the “Remove Duplicates” feature.

  1. 1. Select the columns you would like to check and remove duplicate content for. Here, we will stick to the same columns we highlighted in red.
How to Highlight Duplicates in Google Sheets Select columns 2
How to Highlight Duplicates in Google Sheets - Select columns
  1. 2. Go to Data > Data cleanup > Remove duplicates.
How to Highlight Duplicates in Google Sheets Remove duplicates
How to Highlight Duplicates in Google Sheets - Remove duplicates
  1. 3. A dialogue box should appear where you can select the columns to check. “Select all” simply refers to the column manually selected before, not the whole dataset.
How to Highlight Duplicates in Google Sheets Columns to analyze
How to Highlight Duplicates in Google Sheets - Columns to analyze
  1. 4. If your columns have a header name, make sure to tick the box “Data has header row”. Once finished, click “Remove duplicates”.
How to Highlight Duplicates in Google Sheets Data has header row
How to Highlight Duplicates in Google Sheets - Data has header row
  1. 5. Google Sheets will now show a message informing you about the number of duplicate rows removed. It also lets you know how many unique rows you have. Click “OK”.
How to Highlight Duplicates in Google Sheets Click OK
How to Highlight Duplicates in Google Sheets - Click OK

This built-in feature is the quickest way to remove duplicates in Google Sheets; however, ‌review the content selected before removing since you may delete cells associated with others in a row.

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Conclusion

Highlighting duplicates in Google Sheets is an extremely vital process many users need to carry out to make sure that their datasets are as accurate as possible. Google Sheets has a fantastic data cleanup feature that makes this process quick and easy.

By the end of this article, you should now know how to highlight and remove duplicates in Google Sheets using built-in features and the UNIQUE formula. Although these methods are safe and quick, we always recommend reviewing your selection before removing any data in your worksheet.

If you would like to know more about Conditional Formatting features and applications in Google Sheets, read our blog article Conditional Formatting in Google Sheets (Complete Guide). Prefer to work in Excel? Take a look at the following articles you manage and organize your data better:

Hady ElHady
Hady is Content Lead at Layer.

Hady has a passion for tech, marketing, and spreadsheets. Besides his Computer Science degree, he has vast experience in developing, launching, and scaling content marketing processes at SaaS startups.

Originally published Mar 23 2022, Updated Sep 23 2022