Use this formula in J1 and copy down
=Countif(B$1:B$1000,B1)

Change 1000 to the last row in your dataset.

"SiH23" wrote:

Within Column B there are various product codes. Each code consists of a
mixture of alpha and numerical characters. In Column B some of the codes are
duplicated.

I would like to place a formula in Column J which calculates the number of
individual occurences of that particular product code in Column B.