Celebrating Excel Day 40000

Excel was launched in 1985, so it hasn’t been around for 40,000 days. However,  Excel’s date system starts at January 1, 1900 (day 1), and today is day 40,000 in that date system.

Not on the Mac

It’s not Day 40000 for Excel Mac users though – its default date system starts at January 1, 1904 (day 0).

So, if you’re using Excel for the Mac,  you won’t hit the day 40000 milestone for another four years.

The two dating systems are explained in the Microsoft Knowledgebase article at this link: Description of the differences between the 1900 date system and the 1904 date system in Excel.

Switch to a Different Date System

Whether you’re using Excel on a Windows machine or on a Mac, you can switch from the default date system.

Follow the steps below, if you want to switch to the 1904 Date System in Excel 2007:

  1. Click the Office Button, then click Excel Options
  2. Click the Advanced category
  3. Scroll down to the section titled, When calculating this workbook
  4. Add a check mark to Use 1904 date system.
  5. Click OK
switch from the default date system
switch from the default date system

Keyboard Shortcuts for Dates

If you use these shortcuts, you’ll have more time available for celebrating the 40,000 day milestone.

  • Enter today’s date: Ctrl + ;
  • Format a date as dd-mmm-yy: Ctrl + #

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8 thoughts on “Celebrating Excel Day 40000”

    1. Cool fact: days count in excel is wrong, it is an historical bug inherited from lotus 1-2-3 that has never been fixed to avoid compatibility issues. The day 40000 in excel is actually number 39999. FYI :it will happen again in the year 4000 ad, get your spreadsheets ready :0).

      More info here: https://en.m.wikipedia.org/wiki/Year_1900_problem

  1. Holy Moly, EXCEL nerds unite!! I JUST noticed it, a few days late, and thought to myself, goodness, the date number has started with a 3 the entire time I’ve been using Excel, I’m sure its been years since it changed from 2 to 3 and now to 4. HAPPY 40000!!

  2. Ron, thanks for the correction, and I changed the first line about the 1904 date system.

    InternJessica, I’m pretty sure the Excel Day 40000 party lasts all week, so you’re not too late!

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