Highlight unique values

Generic formula 

=COUNTIF(data,A1)=1

Summary 

Excel contains many built-in "presets" for highlighting values with conditional formatting, including a preset to highlight unique values. However, if you want more flexibility, you can highlight unique values with your own formula, as explained in this article.

If you want to highlight cells that contain unique values in a set of data, you can use a formula that returns TRUE when a value appears just once .

For example, if you have values in the cells A1:D10, and want to highlight cells with duplicate values, you can use this formula:

=COUNTIF($A$1:$D$10,A1)=1