Does the Excel serial date converter upload my serial numbers?

No. Inputs are processed in your browser, and pasted content is not sent to analytics or a server.

What should I paste into the Excel serial date converter?

Choose the workbook date system, then paste one or more serial date numbers.

What can I copy or download?

You can copy the serial-to-date conversion report.

What does the Excel serial date converter not verify?

It does not inspect the original workbook, know which date system a file used, or preserve time-of-day formatting perfectly.

Excel Serial Date Converter

Convert Excel serial date numbers into readable dates with 1900 and 1904 date-system support.

Also useful for: excel serial date converter excel date serial converter spreadsheet serial date 1900 1904 date converter Excel Serial Date Converter

Excel Serial Date Converter

Runs in your browser. Inputs are not uploaded.

Excel Serial Date Converter Example Run

Convert spreadsheet serial numbers into ISO dates.

Sample inputs
Workbook date system: 1900 system
Serial numbers:
45292
25569
60

Generated result
Summary: 3 Excel serial dates converted using the 1900 date system.

Stats
- Serials: 3
- System: 1900

Issues
- Warning: Serial 60 is Excel's historic 1900 leap-year bug date.

Output
45292: 2024-01-01
25569: 1970-01-01
60: 1900-02-28

What the Excel Serial Date Converter Checks

1900 and 1904 systems

The converter supports the two common Excel workbook date systems.
Bulk serial parsing

Serials can be separated by spaces, commas, or new lines.
ISO date output

Each serial is converted into a YYYY-MM-DD date for easy spreadsheet cleanup.
Serial 60 warning

The 1900-system leap-year bug is called out because it can shift historical dates.
Date-only scope

The tool focuses on dates and does not preserve timezone, formatting, or spreadsheet cell metadata.

Excel Serial Date Converter Questions

View all questions

Q: Does the Excel serial date converter upload my serial numbers? A: No. Inputs are processed in your browser, and pasted content is not sent to analytics or a server.
Q: What should I paste into the Excel serial date converter? A: Choose the workbook date system, then paste one or more serial date numbers.
Q: What can I copy or download? A: You can copy the serial-to-date conversion report.
Q: What does the Excel serial date converter not verify? A: It does not inspect the original workbook, know which date system a file used, or preserve time-of-day formatting perfectly.

Related Tools

Updates

v1.0.0 New 2026-05-17: Initial 1900 and 1904 Excel serial date conversion added.