Q: My library in iTunes shows around 500 GB but the iTunes Music folder is over 700 GB. Why are they not the same?
A: To begin, it’s important to ensure that you are reading your iTunes library size properly. The capacity shown at the bottom of the iTunes window reflects the space taken up by the currently selected items, and will be affected by any filters that you have applied. Further, recent versions of iTunes do not provide any easy method to display all of your content in one listing—different types of media are listed in the different categories such as Music, Movies, etc.
Therefore, if you’re viewing your “Music” section, the total capacity shown at the bottom of the iTunes window is only for your actual Music files and does not include other types of content such as Podcasts, Movies, TV Shows, Audiobooks and so forth.
To get a listing of all of the items in your iTunes library for the purposes of a capacity indicator, you can make a Smart Playlist that includes everything, and then read the capacity from the Smart Playlist view. A Smart Playlist with criteria such as Name is not (blank) should suffice for this purpose.
Even if you are looking at the correct capacity information in iTunes, however, it is definitely possible to have more content stored in your iTunes Music folder than is actually listed in your iTunes library.
Firstly, if you add content directly to the iTunes Music folder, the files are of course placed in the folder but iTunes itself does not import these files unless you specifically tell it to, and therefore these new files would not be reflected in your actual iTunes library capacity.
The second scenario is deleting tracks from your iTunes library but leaving them in the iTunes Music folder. This can happen if you choose the “Keep Files” option when deleting tracks from within iTunes itself.
In this case the track gets removed from your iTunes library database, but the file itself will remain in its original location within the iTunes Music folder.