Excel duplicate finder

Three different questions that all get called "duplicates"

The same value twice in one column. Two rows with the same email address, the same invoice number, the same SKU. The rest of the row may differ — that is exactly what makes it worth finding. This is the default mode, and it is what people mean nine times out of ten.

Two rows that are identical across every column. The classic import-run-twice problem. Safe to delete, because nothing is lost.

A value that appears in two columns at once. This is a different job from the other two: you have last month's list in one column and this month's in another, and you want to know what is in both — and, just as often, what is only in one. All three answers come back together, each with its own copy and download button.

What it tells you that Excel's own button does not

Excel's Data → Remove Duplicates deletes rows and reports a count. It does not show you which values were duplicated or where they were, and once it has run, the evidence is gone. That is fine when you trust the data and reckless when you do not.

This page lists every duplicated value with the row numbers it sits on, so you can go and look before anything is deleted. Two downloads are offered — the file without duplicates, and the duplicate rows on their own — because reviewing what you are about to remove is usually the right order of operations.

Case, spaces, and why a "duplicate" gets missed

Bob@example.com and bob@example.com are the same mailbox and different strings. So are ACME Ltd and ACME Ltd  with a trailing space that came from a copy-paste. Leading and trailing spaces are always trimmed here, and case is ignored unless you turn that off — those two rules alone find most of the duplicates a naive comparison misses.

Blank values are skipped rather than being treated as one big duplicate group, which is almost never what anyone wants.

The formula way, for when you need it in the sheet

If the answer has to live in the workbook rather than in a browser tab, the two standard formulas are:

• =COUNTIF(A:A, A2) > 1 in a helper column — TRUE on every row whose value in column A appears more than once.
• =COUNTIF(B:B, A2) > 0 — TRUE when the value in column A also appears anywhere in column B. This is the "two columns" case.

Both work, and both come with a helper column to remember to delete and absolute references that break when someone sorts the sheet. In TableDI the same thing is a formula column that recalculates for rows pasted in next month, written for you by the Dedupe and Match panels in four steps. How the panels work.

Files where "nothing is uploaded" is the point

Deduplication happens on lists of people: subscriber exports, customer records, applicant lists, attendee registrations. Those are the files least suited to being posted to a free web service. This page reads yours in the tab — the code that does it makes no network request at all.