PDF Mikata

Excel Serial Number and Date Converter

When a cell shows a number like 45000 or you need a date as a number.

What you enter is never uploaded. Everything is processed on this device.

  1. 1Enter a value or date
  2. 2Choose the system
  3. 3See the result

Done

🔒 Your files are never sent to an external server. Everything is processed safely inside this browser.

How to use

  1. Enter either a serial value or a date.
  2. Choose the date system (1900 or 1904) if needed.
  3. The other value and the weekday appear.

How it works

  • Excel stores a date as the number of days since a base date, the serial value.
  • Windows versions use the 1900 system and older Mac versions used the 1904 system.

Notes

  • In the 1900 system, the non-existent February 29, 1900 is counted as serial 60.
  • This tool handles dates only, not the time of day (the decimal part).

FAQ

Is what I enter sent anywhere?

No. Everything is processed inside the browser on your device.

What is a serial value?

It is the number of days since a base date, which Excel uses to count dates.

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Guides for this tool

How to Turn an Excel Serial Number into a Date (Free)When a Cell Shows a Number Instead of a DateThe 1900 and 1904 Date SystemsThe Strange February 29, 1900Finding the Weekday of a DateWhat to Do When It Does Not WorkExcel Serial Dates Without Uploading

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