We show you how to highlight duplicates in Google Sheets using the COUNTIF and ARRAYFORMULA functions under the conditional format rules.

Install the Remove Duplicates add-on from the Google Workspace Marketplace. In your sheet, click Extensions, then Remove Duplicates, and choose: Find Duplicates or Uniques.

Once we started using Google Sheets’ built-in tools to highlight duplicates, it became one of those productivity hacks we rely on every single month.