I should give a subtitle of »Oh, so that’s what it does« to this post. So the command we are talking about is HOME/Format/ Default Width…
First I will tell you what it does and then I will show you a trick you can do with it.
What it basically does is it allows you to quickly set the default width of the columns on your sheet. The width is measured in characters and can be anywhere between 0 (means the column is hidden) and 255 (the maximum width). The number means how many characters will be visible if you are using the default font settings. Out of the box the column width is 8.43 characters. So if you open a new Excel workbook, go to HOME/Format/ Default Width… and set it to 50, you get this
Let’s say you have a worksheet that looks like this
Basically you have some content in columns A, B, E and G and at some point you’ve set their width to something else that the default (that is the most important thing), and all the other columns are empty. Now you select the command and give the width of 0 and voila, all the empty columns are now hidden.
Oh, so that’s what it does J So at any point it allows you to set the width of all unused columns and it does nothing to the column that hold some content and have width different than default. Quite brilliant and useful in a way J