How to highlight the duplicates and overlapping dates in Excel?

If there are some programs whose start dates and end dates are overlapping, and how can you highlight the overlapping dates as below screenshot shown? In this article, I introduce two formulas in Conditional Formatting which can solve the job in two cases in Excel.
doc highlight overlapping date 1

Highlight overlapping dates

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Highlight overlapping dates


To highlight the overlapping dates, you can do as below steps:

1. Select the cells which contain start dates and end dates, and click Home > Conditional Formatting > New Rule. See screenshot:
doc highlight overlapping date 2

2. Then in the New Formatting Rule dialog, select Use a formula to determine which cells to format in the Select a Rule Type list, type this formula =SUMPRODUCT(($I2<=$J$2:$J$7)*($J2>=$I$2:$I$7))>1 into the Format values where this formula is true textbox, and click Format. Then in thebdialog, under Fill tab select one color you want to use for highlighting. See screenshot:
doc highlight overlapping date 3

In the formula, I2 is the first start date, J2 is the first end date, I2:I7 and J2:J7 are the start dates column and end dates column.

3. Click OK > OK to close dialogs, and the overlapping dates have been highlighted with the background color.
doc highlight overlapping date 1

If you want to highlight duplicates and overlapping dates as below screenshot shown, you can do as below steps:
doc highlight overlapping date 4

1. Select the data range including start dates, end dates and the program column with duplicates, and click Home > Conditional Formatting > New Rule.

2. Then in the New Formatting Rule dialog, select Use a formula to determine which cells to format in the Select a Rule Type list, and type this formula =SUMPRODUCT(($B2<=$C$2:$C$7)*($C2>=$B$2:$B$7)*($A2=$A$2:$A$7))>1 into the Format values where this formula is true textbox, and click Format. Then in the Format Cells dialog, please enable the Fill tab, and select one color you want to use for highlighting. See screenshot:
doc highlight overlapping date 5

In the formula, B2 is the first start date, C2 is the first end date, B2:B7 and C2:C7 are the start dates column and end dates column, A2 is the first cell in the column you want to find the duplicates, A2:A7 contains duplicates.

3. Click OK > OK to close dialogs.


Select Duplicate & Unique Cells (quickly select duplicate or unique values in a column.

doc highlight duplicate across columns 6

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