Want to know how big a folder is in Mac OS X, including all the files and nested subfolders inside it? This can be very useful, especially when you’re trying to reclaim some disk space. Here’s how to do it.

You can use Finder’s List view (Command-2) to show you the sizes of files in the current folder, but by default all folders show “–” in the Size column:

To change this, choose View > Show View Options (or press Command-J) and enable the Calculate all sizes option:



After a while - depending on how many files you have inside your folders - you’ll see the Size column start to populate with the total size for each folder:



Then it’s simply a matter of clicking the Size column header to find your biggest folders:



You can then click an arrow to the right of a folder to expand it and view the sizes of all its subfolders, and so on. Easy!

 There are other programs that are very useful for finding wasted space on your Mac:

GrandPerspective - GrandPerspective is a small utility application for Mac OS X that graphically shows the disk usage within a file system. It can help you to manage your disk, as you can easily spot which files and folders take up the most space. It uses a so called tree map for visualisation. Each file is shown as a rectangle with an area proportional to the file's size. Files in the same folder appear together, but their placement is otherwise arbitrary.

Disk Inventory X - Mac OS X only: Freeware program Disk Inventory X displays a graphical representation of your hard drive's disk space, giving you a view into what files are taking up the most space on your drive.