Quick answer
Identify duplicate values.
=COUNTIF($A$2:$A$100,A2)>1Example data layout
Use a small table first, confirm the result, then copy the formula down the column.
| Input | Helper value | Result |
|---|---|---|
| A2 | B2 | Formula result |
| A3 | B3 | Copied formula result |
Copy-paste examples
Beginner
Basic Find duplicates example
=COUNTIF($A$2:$A$100,A2)>1Adjust the cell references to match your worksheet layout.
Beginner
Find duplicates copied down rows
=COUNTIF($A$2:$A$100,A3)>1Adjust the cell references to match your worksheet layout.
Intermediate
Find duplicates with clean fallback
=IFERROR(COUNTIF($A$2:$A$100,A2)>1,"")Adjust the cell references to match your worksheet layout.
Intermediate
Find duplicates with structured references
=COUNTIF($A$2:$A$100,[@Input])>1Adjust the cell references to match your worksheet layout.
Advanced
Find duplicates with dynamic data
=COUNTIF($A$2:$A$100,A2)>1Adjust the cell references to match your worksheet layout.
Advanced
Find duplicates inside a report formula
=LET(result,COUNTIF($A$2:$A$100,A2)>1,result)Adjust the cell references to match your worksheet layout.
Step-by-step tips
- Paste the formula into the first result cell.
- Replace sample references like A2, B2, or Table1 with your real cells or table columns.
- Test the formula on two or three rows before copying it down.
- Format the result column as Number, Date, Currency, or Percentage when needed.
- Keep a backup copy of your original data before applying formulas across a large range.
Common mistakes
- Using text values where Excel expects numbers or dates.
- Forgetting quotation marks around text criteria.
- Copying a formula without locking fixed references using dollar signs.
- Applying the wrong number format and thinking the formula is wrong.