Excel Date Converter — Text Dates to Excel Serial Numbers

Turn date text into an unambiguous date and its Excel serial number, without guessing. This tool is for interpreting date text. Changing how a date looks in a cell is a different job — see the date-format guide.

Privacy: this tool runs entirely in your browser. It makes no network requests and has no backend. Nothing you type is uploaded. Closing the page discards it.

Convert dates

Date text — one date per line

Date order

Choose the order your dates are written in. The tool never guesses an ambiguous date.

Excel date system

Check which system your workbook uses before copying a serial back.

Supported separators: slash (/), dash (-), and dot (.). Years must have four digits in this version. A leading four-digit year (for example 2026-05-04) is always read as the year, whatever order you choose.

Results

No results yet — convert at least one date above.

Parsed date (ISO) and Excel serial

How it works

Excel stores a date as a serial number: a count of days from a starting date. In the 1900 system, 1 January 1900 is serial 1. In the 1904 system, 1 January 1904 is serial 0. The two systems differ by 1,462 days for the same calendar date, so the system you choose changes every serial number — always check which system your workbook uses before pasting a serial back.

Parsing vs formatting vs serial numbers

Parsing (this tool): reading date text and deciding which calendar date it means.
Formatting: changing how a date that Excel already understands is displayed, without changing the date itself. See the date-format guide if changing the format does nothing.
Serial numbers: the number Excel stores underneath a date. Two workbooks can show the same date but hold serials 1,462 days apart if one uses the 1900 system and the other uses 1904.

Examples

Example of why the order matters: 04/05/2026 is 4 May 2026 under DMY and 5 April 2026 under MDY. This tool never silently guesses: it applies the order you selected, and it rejects a line it cannot read instead of inventing a date.

Limitations

Numeric dates only in this version. Month names (for example “4 May 2026”) are not accepted yet.
Four-digit years only. A two-digit year (for example 04/05/26) is rejected with a clear message, because the century would be a guess.
Invalid dates are rejected, including 31 February and 29 February in a non-leap year. 29 February 2024 is valid; 29 February 2025 is not.
Dates before 1 January 1900 are rejected in the 1900 system, and dates before 1 January 1904 are rejected in the 1904 system, because those systems have no serial for them.
The 1900 system keeps Excel's historical quirk around February 1900: Excel treats 1900 as a leap year, so 1 March 1900 is serial 61, not 60. This tool follows Excel on that point, and says so, rather than silently using the true calendar.
Results have not yet been verified against a live Excel 365 / Google Sheets file for this site, so check a few converted values in your own workbook before relying on them. Work on a copy of your file.

← Back to home