Quick Look Lets You View Drive Size and Free Space

Available Drive Space is just a Quick Look Away

Quick Look window with four drives selected
Quick Look displaying 4 drives. Screen shot courtesy of Coyote Moon, Inc.

Knowing how much free drive space is available on your Mac is an important part of routine Mac maintenance. As you fill up your Mac's drives with all of the important information you collect, you can end up affecting your Mac's performance, should the free space drop too low.

There are a few different methods to determine available free space, including using Disk Utility, the Finder, and even Terminal.

But ever since OS X Snow Leopard was released in the summer of 2009, there has been a very easy, and perhaps more important, extremely quick way to discover just how large a drive is, and the amount of free space it has available.

But wait, there's more. Not only can you see the size and available free space of a selected drive, you can also get the size and free space of as many drives as you have connected to your Mac.

Quick Look

You probably didn’t guess that Quick Look was the super-fast and easy way to access your Mac's drive size and free space, but it is. Quick Look was originally designed to let you see the content of files without having to open them in a particular app. Quick Look is a great way to see if the text file named My Summer Vacation is actually about last summer's vacation. Just place your cursor over the file's icon, hit the space bar, and the content of the file will be displayed.

This trick works because Quick Look knows all about the various text file types and can display the file's content, properly formatted, in the Quick Look window. Quick Look works with most file types, including most of the Microsoft Office files, and just about all image types. But it also works with folders and drives, letting you see the size of a folder, and the size and amount of free space on a drive.

Quick Look can perform all of this magic due to its understanding of various file types, as well as its ability to make use of Quick Look plug-ins to add support for new file types that Apple hasn't included in its skill set. You don’t need to add any plug-ins for the drive space functions demonstrated in this article, but if you're intrigued by the capabilities of Quick Look, you can find a list of available plug-ins at the QuickLook Plugins List.

Quick Look for Drive Space

  1. On the desktop or in a Finder window, select a volume you wish to check for available space.
  2. With the volume selected, press the space bar.
  3. Quick Look will display the total disk space on the volume, and the amount of free space available.

Quick Look for Multiple Drives

If you have multiple drives connected to your Mac (you should have a minimum of two: a startup drive, and a backup drive), you can use Quick Look to discover the size and free space on as many drives as you wish.

  1. If you have your Mac's drives visible on the desktop, or in the Finder's sidebar, you can select multiple drives by holding down the shift key as you select each drive.
  2. Once all the drives you wish to examine are selected, press the space bar.
  3. Quick Look will open and display one of the selected drive's icon, its size, and the amount of free space.
  1. You can examine the next drive you selected by clicking the forward arrow key at the top left of the window.
  2. You can also display the complete list of selected drives by clicking on the icon view button (it looks like the same as the icon view button used in the Finder).
  3. In icon view, the Quick Look window will display the icons of all the selected drives, allowing you to click on the drive you wish to examine.

One Last Quick Look Trick

Our last Quick Look window trick isn't specific to looking at drive size and free space, but is just a function of any Quick Look window you may open. Once a Quick Look window is frontmost on your Mac's desktop, you can select any file or drive on your Mac, and its content will be displayed in the Quick Look window, all without having to unselect an item or press the space bar again.

This lets you view files or drives quickly.

Quick Look is quite versatile, and all it takes to make use of the feature is to remember the power of the space bar.