Conditional Formatting To Red out a Row, if ID# has been used before


Hi all,

I am trying to create a conditional formatting to mark a row Red if the ID# has been used before. I have plenty of conditional formatting experience however I just can't seem to figure this part out. Basically in a list of projects I.e 1,2,3,4,5 they move at different speeds and sometimes a project wont be on a newer sheet so numbering can get confusing. If a 2nd project were to be added as project 4, I would want both to go red so I know to update 1 of them.


  • ker9
    ker9 ✭✭✭✭✭✭

    Hi @Mathew Palter

    You may need a helper column to count duplicates and base your conditional formatting on that column.

    =IF(COUNTIF([ID#]:[ID#], [ID#]@row) > 1, 1, 0)

    Where the formula returns "1" there is a duplicate.

    You could change it to use text if you prefer.

    =IF(COUNTIF([ID#]:[ID#], [ID#]@row) > 1, "DUP", "OK")

    Hope this helps!

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