Spreadsheet utility
Excel Date Serial Converter
Convert between real dates and Excel serial date numbers without sending data to a server.
Builder inputs
Use ISO dates for reliable conversion.
460232026-01-01This converter uses Excel's common 1900 date system, including the historical serial 60 leap-year bug. It does not use the older 1904 date system.How this formula works
- Excel stores dates as serial numbers, where each day increments by one.
- Modern Excel commonly uses the 1900 date system, including its historical leap-year bug.
- This utility does not convert the legacy 1904 date system used by some older Mac workbooks.
- Google Sheets can display serial date numbers too, but date system behavior can vary by import context.
Sample data
| Date | Excel Serial |
|---|---|
| 2026-01-01 | 46023 |
| 2026-05-12 | 46154 |
| 2027-01-01 | 46388 |
Common mistakes
- Dates formatted as text may not convert correctly in spreadsheets.
- Time values add decimal fractions to serial numbers.
- Serial 60 is the 1900 leap-year compatibility edge case; 1904-system workbooks need manual adjustment.
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.