How to Set the Default Column Size in Mac OS X Finder Windows
The Mac OS X Finder column view is really handy, letting you see multiple folder contents side by side in a hierarchical view. But unless you set the default column width yourself, anytime you launch a new Finder window, the columns size will be reset on a per window basis.
Changing this behavior is very simple, and if you want to set the default column size for Column View in Finder of OS X, all you need to do is hover the mouse cursor over the column dividers of a Finder window, then hold down the Option key while dragging the columns to your desired width or size.
With the Option key modifier held as you resize, this will become the new default for Column Views in the Mac Finder.
This works in all versions of Mac OS X that support Column View, and it’s an easy trick to remember even if it’s not the most obvious thing in the world. If you’re a column view user, try it out, you’ll find this to be quite useful.
Note that the Option key trick is intended for most keyboards and US keyboard set, but some users may find the Command key to work depending on their keyboard layout and keyboard country settings. Let us know in the comments what works for you. And yes, you must be in Column View to have this work, it does not work in the other Finder views since there is no divider to align and set the width of.