How to highlight duplicates in Google Sheets

In my previous blog post, I described different means to find and process duplicates in your spreadsheet. But in order to spot them instantly, it would be best to highlight them with color.

And today I will try to cover the most popular cases for you. You will highlight duplicates in Google Sheets using not only conditional formatting (there are different formulas based on the spread of duplicates in your table) but also a special add-on.

Highlight duplicate cells in a single Google Sheets column

Let's start with the basic example. It is when you have just one column with repeated values:
One-column data with duplicates.

Tip. I'm going to use conditional formatting in every but the last case today. If you're not familiar with it, get to know it in this blog post.

To highlight duplicate cells in one Google Sheets column, open conditional formatting and set the following options:

  1. apply the rule to your range of cells — A2:A10 in my example
  2. pick Custom formula from the drop-down with the condition and enter the following formula:

    =COUNTIF($A$2:$A$10,$A2)>1

    Note. There's a dollar sign next to the letter for A2. It is intentional so the formula could count each cell from column A. You will learn more about cell references in this article.
  3. select any color from the Formatting style to highlight those duplicates
  4. click Done

That COUNTIF formula will scan your column A and tell the rule which records appear more than once. All these duplicate cells will be colored according to your settings:
Highlight duplicates in one Google Sheets column.

Highlight duplicates in multiple Google Sheets columns

It may happen that repeated values will be in more than one column:
Several columns with repeated values.
How do you scan and highlight duplicates in all 3 Google Sheets columns then? Using the conditional formatting as well. The drill is the same as above with a few slight adjustments:

  1. select A2:C10 as a range to color repeated cells within
  2. change the range for Custom formula as well:

    =COUNTIF($A$2:$C$10,A2)>1

    Note. This time, remove the dollar sign from A2. This will let the formula count all occurrences of each cell from the table, not just from column A.
    Tip. Read this article to learn more about relative, absolute, & mixed cell references.
  3. pick a color in the Formatting style section and hit Done

Highlight all duplicate cells in all Google Sheets columns.
Unlike the aforementioned COUNTIF, this one scans all 3 columns and counts how many times each value from the table appears in all columns. If more than once, conditional formatting will highlight these duplicate cells in your Google Sheets table.

Highlight the entire row if duplicates are in one column

Next up is the case when your table contains different records in each column. But the entire row in this table is considered as a single entry, a single piece of information:
A table with duplicates in column B.
As you can see, there are duplicates in column B: pasta & condiment sections occur twice each.

In cases like this, you may want to treat these entire rows as duplicates. And you may need to highlight these duplicate rows in your Google spreadsheet completely.

If that's exactly what you're here for, make sure to set these for your conditional formatting:

  1. Apply the rule to the range A2:C10
  2. And here's the formula:

    =COUNTIF($B$2:$B$10,$B2)>1

Highlight entire rows if duplicates are in one column.
This COUNTIF counts records from column B, well, in column B :) And then the conditional formatting rule highlights not just duplicates in column B, but the related records in other columns as well.

Highlight complete row duplicates in spreadsheets

Now, what if the entire row with records in all columns appears several times in your table?
Absolute duplicate rows in your table.
How do you check all 3 columns through the table and highlight absolute duplicate rows in your Google sheet?

Using this formula in conditional formatting:

=COUNTIF(ArrayFormula($A$2:$A$10&$B$2:$B$10&$C$2:$C$10),$A2&$B2&$C2)>1
Highlight absolute duplicate rows in Google Sheet.
Let's break it down into pieces to understand how it works:

  1. ArrayFormula($A$2:$A$10&$B$2:$B$10&$C$2:$C$10) concatenates every 3 cells from each row into one text string that looks like this: SpaghettiPasta9-RQQ-24

    Thus, in my example, there are 9 such strings — one per row.

  2. Then COUNTIFS takes each string (starting from the first one: $A2&$B2&$C2) and looks for it among those 9 strings.
  3. If there's more than one string (>1), these duplicates get highlighted.
Tip. You may learn more about COUNTIF and the concatenation in Google Sheets in the related articles.

Highlight actual duplicates — 2n, 3d, etc instances

Let's suppose you'd like to keep the 1st entries of duplicate rows intact and see all other occurrences if there are any.

With just one change in the formula, you'll be able to highlight these 'real' duplicate rows — not the first entries, but their 2nd, 3rd, 4th, etc instances.

So here's the formula I suggested right above for all duplicate rows:

=COUNTIF(ArrayFormula($A$2:$A$10&$B$2:$B$10&$C$2:$C$10),$A2&$B2&$C2)>1

And this is the formula you need to highlight only duplicate instances in Google Sheets:

=COUNTIF(ArrayFormula($A$2:$A2&$B$2:$B2&$C$2:$C2),$A2&$B2&$C2)>1
Color actual duplicates via the Google Sheets conditional formatting.
Can you see the difference in the formula?

It's in the first COUNTIF argument:

$A$2:$A2&$B$2:$B2&$C$2:$C2

Instead of mentioning all rows like in the first formula, I use only the first cell of each column.

It lets each row to look only above to see if there are the same rows. If so, every current row will be treated as another instance or, in other words, as an actual duplicate that will be colored.

Formula-free way to highlight duplicates — Remove Duplicates add-on for Google Sheets

Of course, you may have some other use case that requires another formula. Nonetheless, any formula and conditional formatting require a learning curve. If you're not ready to devote your time to those, there's an easier solution.

Remove Duplicates add-on for Google Sheets will highlight duplicates for you.

It takes just a few clicks on 4 steps, and the option to highlight found duplicates is just a radio button with a color palette:
Fill found values with color.
The add-on offers an intuitive way to select your data and pick columns you'd like to check for duplicates. There's a separate step for each action so you won't get confused:
Select columns to search in.
Besides, it knows how to highlight not only duplicates but also uniques. And there's an option to ignore 1st instances as well:
Choose the type of data you want to find.
Just install Remove Duplicates from the Google Sheets store, try it on your data, and you'll see how much time and nerves you will save on getting those records colored correctly. Yes, without any formulas and in just in a few clicks ;)

Tip. Here's a video that shows the add-on in action. It may be a bit old since at the moment the add-on has more to offer, but it's still the same add-on:

Spreadsheet with formula examples

Highlight duplicates in Google Sheets - conditional formatting examples (make a copy of the file)

You may also be interested in

Ukraine flag War in Ukraine! To support Ukraine and save lives please visit this page.