OS X Can Map Your Hard Drive Space Usage by File Type

What's taking up all of your storage space?

About This Mac - Storage Map
The System Profiler displays volume data organized by data type. ​ 

Wondering what's taking up space on any or all of your drives? Perhaps your startup drive is getting full, and you would like some insight into which type of file is hogging all the room.

Before OS X Lion, you had to use third-party disk tools, such as DaisyDisk, to decipher which files were taking up the majority of space. While third-party tools may still be the best choice for zeroing in on individual files taking up space, you can now use a feature of OS X to help discover who the data hogs are.

About This Mac Storage Map

Starting with OS X Lion, the OS now has the ability to show you how much ​drive space is being used for specific file types. With just a click or two of the mouse or trackpad, you can see a graphical representation of the file types stored on your drives, and find out how much space each type of file is taking up.

At a glance, you can tell how much space is devoted to Audio Files, Movies, Photos, Apps, Backups, and Other. While the list of file types isn't long, it lets you quickly see which type of data is taking up more than its share of your storage space.

The storage map system isn't perfect. With a Time Machine backup drive, none of the files were listed as Backups; instead, they were all listed as Other.

Third-party apps do a much better job of displaying this type of storage information, but when you remember that this is a free service of OS X, its inability to offer a more detailed view can be forgiven. The storage map provides a very useful and quick overview of how the space on your drives is being utilized.

Accessing the Storage Map

The storage map is part of the System Profiler, and is easy to access.

If You're Using OS X Mavericks or Earlier

  1. From the Apple menu, select About This Mac.
  2. In the About This Mac window that opens, click the More Info button.
  3. Select the Storage tab.

If You're Using OS X Yosemite or Later

  1. From the Apple menu, select About This Mac.
  2. In the About This Mac window that opens, click the Storage tab.

Understanding the Storage Map

The storage map lists each volume connected to your Mac, along with the size of the volume and the amount of available free space on the volume. In addition to the basic information about the volumes, each volume includes a graph showing what type of data is currently stored on the device.

Along with the storage map, you'll also see the amount of storage taken up by each file type, expressed in numbers. For instance, you may see that Photos take up 56 GBs, while Apps account for 72 GBs.

Free space is shown in white, while each file type has a colored assigned to it:

  • Apps: green
  • Audio: orange
  • Backups: pink
  • Movies: yellow
  • Photos: magenta
  • Other: blue

The "other" category is so poorly defined that you may find the majority of your files falling into this category. This is one of the knocks against the built-in storage map.