Using Array Formulas in Excel – Find if a list has duplicate items

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Find a list is unique or not using array formulas in excelToday I have learned this very cool way to find if a list has duplicate items or not.

This technique uses array formulas (do not shudder, believe me they are not as difficult as you may think)

First the formula

Assuming your list is in the range, C3: C9, the array formula to find if a list has duplicate items or not is,

=IF(MAX(COUNTIF(C$3:C$9;C3:C9))>1,"list is not unique","list is unique")

Now the explanation

How do you know if a list has no duplicates? Simple, we find the number of times each item has appeared in the list and see if any of those counts are more than 1.

Now, take a look at the formula. It says find the maximum of individual item counts using countif (learn excel countif function) and if the maximum is more than 1, then the list has duplicates, otherwise it is unique.

But…

Yes, entering the formula will not work by itself. You have to make it array formula.

How do you do that?

Oh, that is simple, you just take the excel spreadsheet and whack it until it turns blue.

well, not really. all you need to do is enter the formula and press CTRL + SHIFT ENTER instead of just pressing enter.

that way excel converts your formula to array formula and the COUNTIF(C$3:C$9,C3:C9) will return an array of counts instead of one value. Now you can also guess why we have absolute reference for one parameter of countif () and relative reference for another. Learn more about Absolute and Relative References in excel formulas.

More on Finding and Removing Duplicate Items

> Using pivot tables to get unique items in excel
> Getting unique items using data filter and formulas
> Use advanced data filters to find unique items
> Eliminate Duplicate Entries in a List using Formulas
> Get Unique items using Excel 2007 built in features

This post is part of our Spreadcheats series, a 30 day online excel training program for office goers and spreadsheet users. Join today.

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3 Responses to “How-to create an elegant, fun & useful Excel Tracker – Step by Step Tutorial”

  1. Malani says:

    Hi Chandoo,
    I am responsible for tracking when church reports are submitted on time or not and the variations from the due date for submission.
    Here is the Scenario;
    The due date for the submission of monthly reports is on the 5th of each month. and I would like to know how many reports have been submitted on time (i.e, those that have been submitted on or before the due date) I would also want to track those reports that have been submitted after the due date has passed.
    How can I create such a tracker?

  2. Carl says:

    Hi Chandoo,
    I am a member of your excel school.
    I was trying to create SOP Tracker I follow all your steps but I keep this error below.

    The list source must be a delimited list, or a reference to a single row or cell.

    I try looking on YouTube for answer but no luck.

    can you help on this?

    thanks
    Carl.

  3. Rakesh says:

    Dear Mr. Chando,

    Rakesh, I'm working in a private company in the UAE. Recently, I'm struggling to get more details about the staff sick, annual, unpaid, and leaves. I would like to get a tracker in excel. Could you please help me in this situation?

    I also watching your videos in YouTube. i hope you can help me on this situation.

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