In Excel: add a helper column with =IF(COUNTIF(A:A,A2)>1,"Duplicate","Unique"), then filter that column to "Duplicate" to list every repeat.
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What this does
The fastest way to locate duplicates without changing your data is a COUNTIF helper column. COUNTIF(A:A,A2) counts how many times the value in A2 appears in the whole column; if that count is above 1, the value is repeated. Wrapping it in IF turns each row into a plain "Duplicate" or "Unique" flag you can then filter, sort or count — a reversible, auditable trail that leaves the original column untouched. Most people learn this as a sequence of clicks and forget it by next week; learning it as a pattern instead is what lets you apply it to the next, slightly different version of the problem without starting from scratch. That is the difference this page is trying to make. For “excel show duplicates only”, the reliable version is a short checking loop, not just the first command that appears to work. Run it on a deliberately small range first, watch how the affected duplicates change, and only then apply the same setup to the full sheet. When a formula is involved, keep the inputs labelled beside it, reference cells instead of typing values, and apply number formatting only after the result checks out. That is what makes a data step that keeps your analysis trustworthy useful in real work: repeatable, auditable, and not dependent on memory or luck.
A worked example
A column A2:A11 of order IDs reads 1001, 1002, 1003, 1004, 1005, 1004, 1006, 1007, 1003, 1008. In B2 enter =IF(COUNTIF(A:A,A2)>1,"Duplicate","Unique") and fill down. Both rows holding 1004 and both holding 1003 are flagged "Duplicate"; every other row reads "Unique". Switch on a filter and pick "Duplicate" to see only the four repeated rows. When you need to investigate duplicates rather than silently delete them — auditing IDs, reconciling imports, chasing down why a total is off — a COUNTIF flag is the transparent tool: every repeat is listed, countable and reversible. A practical tip before you scale it up: build it once on a small block of test data, confirm the number against the tool on this page, and only then point it at your real sheet. That one habit catches almost every mistake while it is still cheap to fix, long before a wrong figure reaches a report or a colleague.
In Google Sheets
If you are in Google Sheets rather than Excel, the good news is that the formula shown here is identical and the workflow barely changes — menus sit across the top instead of in a ribbon, and a few function names differ slightly, but anything you build here moves across with little or no rework. The aim was to get you unstuck fast and leave you a little more capable than a copy-paste would. The answer is at the top, the tool proves it, and the detail above shows why it holds — so the next time a colleague asks, you can answer without reaching for search. Treat “excel show duplicates only” as a small building block rather than a chore. Once the inputs sit in their own cells and the formula reads from them, the same setup answers a dozen related questions with a tweak, and Excel keeps every dependent figure current as the data changes. The tool above is there so you can rehearse and verify before committing anything to a real workbook; the steps and worked example are there so the logic sticks. Get it right once and it stops costing you time — it starts saving it, every time the question comes back around.
Common mistakes
- Locking the wrong reference — keep
A2relative so it moves down, but use a whole-column range likeA:A(or an absolute$A$2:$A$100). - Trailing spaces or mixed case hiding true matches;
COUNTIFis case-insensitive but spaces still split values, so clean withTRIMfirst. - Expecting the helper column to delete anything — it only flags; removing rows is Data ▸ Remove Duplicates.
- Pointing
COUNTIFat a single cell instead of the full column, so nothing is ever counted as repeated.
Frequently asked questions
How do I flag only the second and later occurrences?
Use a growing range: =IF(COUNTIF($A$2:A2,A2)>1,"Duplicate","") marks every repeat after the first, leaving the original unflagged.
Can I find duplicates across two columns?
Combine the keys first: =IF(COUNTIFS(A:A,A2,B:B,B2)>1,"Duplicate","Unique") treats a row as duplicate only when both columns match.
Does this change my data?
No. A helper column is purely additive — delete the column and your original list is exactly as it was.