Excel duplicate finder

How to find duplicates in Excel without a formula

1. Open the file. Drop the .xlsx or .csv onto the box. It is read in your browser and is never uploaded.
2. Say what counts as a duplicate. Repeated values in one column, rows that are identical across every column, or values that appear in two columns at once.
3. Read the groups. Each duplicated value is listed with how many times it appears and which rows in the file it sits on, so you can go and look at them.
4. Take the clean file. Download the sheet with duplicates removed, or download just the duplicate rows to review before deleting anything.

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.

The three ways Excel itself finds duplicates

Worth knowing before you leave the workbook, because two of them take about four clicks. All three are in Excel for Windows, Excel for Mac and Excel on the web.

• Conditional Formatting → Highlight Cells Rules → Duplicate Values. Select the column, apply it, and every repeated value turns pink. It marks duplicates in place — it does not tell you how many there are, which values they are, or which rows. It is also comparing only inside whatever you selected, which is the usual reason it "misses" one.
• Data → Remove Duplicates. Deletes the extra rows and reports a count like "12 duplicate values found and removed; 488 unique values remain". Fast, and irreversible once you save: the rows it took are gone and it never showed you which they were.
• A COUNTIF helper column. The one that survives being sorted and re-run next month — see the formula way below for the two you need.

None of the three answers the two-column question ("which values are in both lists"), and none of them gives you a list you can hand to somebody else. That is the gap this page fills.

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 third cause is the one nobody looks for, because it is invisible on screen. The é in José can be one character (U+00E9) or two (e followed by a combining accent, U+0301); ＡＢＣ Ltd in full-width characters is not ABC Ltd. They render identically and compare as different strings, so Excel leaves both rows standing. Ignore full-width and accent-composition differences runs Unicode NFKC before comparing, which merges those writings. It affects the comparison only — the file you download keeps the original spelling.

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.

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.