The formula is based on the AND function, configured with two conditions. The first conditions checks to see if the column date is greater than or equal to the start date: The second condition checks that the column date is less than or equal to the end date: When both conditions return true, the formula returns TRUE, triggering the blue fill for the cells in the calendar grid. Note: both conditions use mixed references to ensure that the references update correctly as conditional formatting is applied to the calendar grid.

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.