Count Duplicate Values in Excel
Count how often each key appears.
What this solves
Validate that each HU appears exactly once. This pattern is useful when the business question is clear but a generic tutorial is too abstract.
The rule
COUNTIF against the key column returns the occurrence count.
=COUNTIF($A:$A,A2)Google Sheets: The core pattern is also usable in Google Sheets; exact function support and locale separators can differ.
Real-work checklist
- Define the business key and expected grain before writing the formula, query or markup.
- Test the pattern on a small known sample where you can verify the answer manually.
- Check missing values, duplicates and data types before trusting a large result.
- Scale to the real file or database only after the logic is proven.
Common mistake
If case sensitivity matters, COUNTIF may not be enough; use a stricter method.