# Find duplicate values in two columns

To highlight duplicate values in two or more columns, you can use conditional formatting with on a formula based on the COUNTIF and AND functions.

In the example shown, the formula used to highlight duplicate values is:

Both ranges were selected at the same when the rule was created.

### How this formula works

This formula uses two named ranges, "range1" (B5:B12) and "range2" (D5:D10).

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.

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