This tutorial will walk you through how to use the COUNTIF formula on Microsoft Excel to see if entries of a specified column are also present in another column.

I need to compare numbers in two columns of Excel to find duplicates in data. Both columns have essentially the same numbers, but Column B has multiple instances of the same number. Column A is unique. How can I ascertain if every number in Column A is present in Column B at least once? How can I find the number that is missing from Column B?

A B B.121 S.222 S.154 B.121 B.164 S.154 B.187 B.154

Solution

Find duplicates in your data by using the COUNTIF formula. This can be done by first adding an additional column to your table. Assuming your data in Columns A and B begin at line two, insert the following formula into Column C2:

=COUNTIF(B:B,A2)

The resulting number shown in Column C2 will tell you how many times the value in A2 appears in column B.

Compare all data in the table by highlighting C2 and dragging the formula to the last row of data entry in Column C.

More tips about comparing and pasting in Excel can be found here: