In the example shown, the formula used to highlight duplicate values is: Both ranges were selected at the same when the rule was created. The core of this formula is the COUNTIF function, which returns a count of each value in both range inside the AND function: COUNTIF will either return zero (evaluated as FALSE) or a positive number (evaluated as TRUE) for each value in both ranges. If both counts are positive (i.e. non-zero), the AND function will return TRUE and trigger the conditional format.

Dave Bruns

Hi - I’m Dave Bruns, and I run Exceljet with my wife, Lisa. Our goal is to help you work faster in Excel. We create short videos, and clear examples of formulas, functions, pivot tables, conditional formatting, and charts.