Article updated on August 19, 2017

Question: How do I filter duplicates with a condition?


Column B contains category and column C contains Items. Only duplicate Items with adjacent Category number 2 is listed in column E.

AA is in category 2 (row 3) and 1 but exists only once in category 2. It is not a duplicate.

BB is in category 2 and exists twice (row 4 and 9). BB has a duplicate.

CC is in category 2 and has a duplicate (row 6 and 8). CC is a duplicate.

Formula in cell E4:

=LOOKUP(2, 1/(((COUNTIF($E$3:E3, $C$3:$C$9)=0)*(COUNTIFS($B$3:$B$9, $F$2, $C$3:$C$9, $C$3:$C$9)>1))), $C$3:$C$9)

If you want duplicates sorted from A to Z, read this article:

Extract a list of alphabetically sorted duplicates from a column

Question: How do I create a new list of alphabetically sorted duplicates using excel array formula? Answer: Excel array formula […]

Learn how to filter duplicates:

Extract a list of duplicates from a column

The array formula in cell C2 extracts duplicate values from column A. Only one duplicate of each value is displayed […]

You can also use more than one condition, this article shows you how:

Filter duplicate values using critera

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Explaining formula in cell E4

Step 1 - Identify values that has not been displayed before

COUNTIF($E$3:E3, $C$3:$C$9)=0


COUNTIF("Duplicate items",{"AA";"BB";"AA";"CC";"AA";"CC";"BB"})=0

and returns


In cell E4 no values has been shown before so the array returns TRUE for all values.

How to use the COUNTIF function

Counts the number of cells that meet a specific condition.

Step 2 - Find duplicates in category 2

COUNTIFS($B$3:$B$9, $F$2, $C$3:$C$9, $C$3:$C$9)>1


COUNTIFS({2;2; 1;2;1; 2;2}, 2, {"AA";"BB";"AA";"CC";"AA";"CC";"BB"}, {"AA";"BB";"AA";"CC";"AA";"CC";"BB"})>1




How to use the COUNTIFS function

Checks multiple conditions against the same number of cell ranges and counts how many times all criteria are met.

Step 3 - Multiply arrays

(COUNTIF($E$3:E3, $C$3:$C$9)=0)*(COUNTIFS($B$3:$B$9, $F$2, $C$3:$C$9, $C$3:$C$9)>1)



and returns {0;1; 0;1;0; 1;1}

Step 4 - Divide 1 with array

1/(((COUNTIF($E$3:E3, $C$3:$C$9)=0)*(COUNTIFS($B$3:$B$9, $F$2, $C$3:$C$9, $C$3:$C$9)>1)))


1/{0;1; 0;1;0; 1;1}

and returns {#DIV/0!; 1;#DIV/0!; 1;#DIV/0!; 1;1}

Step 5 - Find last matching value in array

The LOOKUP function ignores errors but requires the second argument to be sorted ascending. However our list contains only errors or 1 so the LOOKUP function returns the last matching 1 in the array.

LOOKUP(2, 1/(((COUNTIF($E$3:E3, $C$3:$C$9)=0)*(COUNTIFS($B$3:$B$9, $F$2, $C$3:$C$9, $C$3:$C$9)>1))), $C$3:$C$9)


LOOKUP(2, {#DIV/0!; 1;#DIV/0!; 1;#DIV/0!; 1;1}, $C$3:$C$9)


LOOKUP(2, {#DIV/0!; 1;#DIV/0!; 1;#DIV/0!; 1;1}, {"AA";"BB";"AA";"CC";"AA";"CC";"BB"})

and returns "BB" in cell E4. BB is the corresponding value to the last 1 in the array, bolded above.

How to use the LOOKUP function

Finds a value in a sorted cell range and returns a value on the same row.

Step 6 - Relative cell refences

The following cell reference is both an absolute and relative cell reference: $E$3:E3. When you copy the formula to cells below, the cell ref changes. That way the formula knows which values have been displayed before.

How to use absolute and relative references

What is a reference in Excel? Excel has a A1 reference style. Columns are named letters A to XFD. Total […]

Download excel example file

Filter duplicates with a condition.xlsx

(Excel Workbook *.xlsx)