How to compare data in two columns to find duplicates in Excel

You can use the following method to compare data in two Microsoft Excel worksheet columns and find duplicate entries. 

Use a worksheet formula

1. Start Excel.

2. In a new worksheet, enter the following data as an example (leave column B empty):

   	A	B	C
   1	1		3
   2	2		5
   3	3		8
   4	4		2
   5	5		0

3. Type the following formula in cell B1:

   =IF(ISERROR(MATCH(A1,$C$1:$C$5,0)),"",A1)

4. Select cell B1 to B5.

5. Select Fill in the Editing group, and then select Down.

   The duplicate numbers are displayed in column B, as in the following example: 

   	A	B	C
   1	1		3
   2	2	2	5
   3	3	3	8
   4	4		2
   5	5	5	0