Excel formula builder
Duplicate Checker Formula Builder
Create a formula that flags duplicate IDs, SKUs, emails, or names while ignoring blank rows.
Builder inputs
Use the full range to check and the current row cell where the formula starts.
=IF(A2="", "", IF(COUNTIF($A$2:$A$100, A2)>1, "Duplicate", ""))COUNTIF checks the current value against the chosen range. The blank guard prevents empty rows from being marked as duplicates.How this formula works
- COUNTIF returns how many times the current value appears in the chosen range.
- The default formula ignores blanks before running the duplicate check.
- Use the after-first mode when you want to keep the first occurrence unmarked.
Sample data
| SKU | Item | Category | Price |
|---|---|---|---|
| A-100 | Keyboard | Hardware | 49 |
| A-101 | Mouse | Hardware | 25 |
| B-200 | Desk Mat | Office | 18 |
| B-201 | Notebook | Office | 7 |
Common mistakes
- Use absolute references for the full check range before filling the formula down.
- Leading or trailing spaces can hide duplicates that look identical.
- Choose after-first mode if the first item should remain clean.
Related formulas
FAQ
Are these formulas generated with AI?
No. The builder uses deterministic TypeScript functions in the browser and does not call any AI API.
Do I need to upload my spreadsheet?
No. Enter ranges and criteria manually. The site does not upload, store, or process spreadsheet files.
Can I copy the generated formula?
Yes. Each output includes a copy button so you can paste the formula into Excel or Google Sheets.