Automatically Run a Macro When a Workbook is Opened

You need this macro code:

The trick is that you must put this macro code into ThisWorkbook

Steps to Make a Macro run When a Workbook is Opened

1. Hit Alt + F11 on the keyboard to get to the Macro editor.
   
2. Then, instead of creating a Module, which is what we usually do, we double-click where it says ThisWorkbook:
   
3. In the window that appears, go to the left drop down menu and select Workbook:
   
4.  If the default text for Open doesn't appear, then look to the right drop down menu and select Open from the list:
   
5. Type whatever macro code you want to run in the middle and that's it!
   

Make sure to download the accompanying workbook to see this macro in action.

Macro Might Not Run Automatically If...

Doing this does not mean that a macro will always run when a workbook is opened.  Due to security features in Excel, many workbooks will have macros turned off by default.  In order for this to run, the macros have to be enabled.

You may see a warning when you open a workbook with a macro in it and you will then have to enable the macros from that warning.

However, some people will have all macros turned off without notification, which means they will not see an option to turn them on.

All of this just means that you cannot plan for all of your users to have macros turned on by default and, as such, you shouldn't have mission-critical macros run in this manner.

In another tutorial, I'll show you how to make users enable their macros in order to view the workbook so that a problem like this can be avoided.