Mac

The 5 Best Free Apps to Check Disk Space Storage on Mac

Rahul Saigal Updated 20-03-2020

If your Mac is running low on disk space or you’ve seen that scary “startup disk is full” message, you know it can be frustrating to free up storage. To deal with this problem, many people resort to external drives and juggle their files continuously between the disks.

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While you can manually track available storage space, we’ll show you how to check disk space on a Mac using some disk analyzer apps. They offer unique visual experiences and let you take actionable steps to free up valuable disk space.

How to Check Hard Drive Space on Mac

There are multiple ways to check the storage space on your Mac. Choose Apple menu > About This Mac and click Storage for the most basic one. Hover your pointer over the colored blocks to see what kind of content is using disk space.

see the disk space using about this mac

For more info, open Disk Utility by searching for it with Spotlight (Cmd + Space). Select your startup volume from the left panel to check the amount of used space in the volume.

Then, click the Info button in the toolbar to show more details like Purgeable space and Available space (Purgeable + Free).

disk space information in detail using disk utility

For another method, right-click the Macintosh HD disk icon on the left sidebar in Finder and select Get Info. You’ll get details on Used versus Available capacity, along with the space macOS considers purgeable.

disk space through get info menu

What Is “Other” in Mac Storage?

On some Macs, you’ll notice that the Other storage category takes up a lot of disk space. This includes macOS system files, user Library folders, cache folders, and more. The majority of these folders are not normally visible.

If you mess with these directories, it could result in an unstable system, loss of data, or even prevent your Mac from booting up. Find out more about macOS folders you shouldn’t touch 5 macOS Folders You Should Never Touch (And Why) If your Mac is running low on space, you might be tempted to delete these folders---but it's dangerous to touch them. Read More and how to handle them if they use a lot of space.

Why You Should Use a Mac Disk Space Analyzer

Why would you use a third-party app when there are multiple built-in ways to check the disk space on your Mac? Here are some reasons:

  • Finder might incorrectly interpret hard links as another copy of the file. Although hard links take no actual disk space, Finder counts them (at least) twice as distinct files, resulting in inaccurate estimation of folder sizes.
  • Your Mac’s file system, APFS New macOS, New Filesystem: What Is APFS and How Does It Work? iOS already has APFS. Now it's the Mac's turn. But what exactly are we getting into this Fall? Read More , uses space-efficient clones while copying a file within the same volume. Instead of duplicating the data, it updates the metadata, and the on-disk data gets shared. Finder does not understand this mechanism and wrongly estimates free and used disk space.
  • The APFS snapshot feature works differently. When Time Machine creates local snapshots, the file system is aware of the changes. But neither Finder or About This Mac shows the space taken by snapshots. As a result, it may show the System category taking a lot of space.
  • In APFS, every disk is a container that can hold multiple volumes and shares the same pool of free space. If your startup disk consists of at least four separate volumes, you might notice a reduction in space available to Macintosh HD.

Now that you know why we recommend you use third-party apps, let’s explore the best Mac disk space analyzers to inspect and analyze disk space.

1. GrandPerspective

GrandPerspective user interface

GrandPerspective is a utility app that uses a treemap structure for visualizing disk space. Upon launch, it asks you to select a folder or drive you want to analyze. A view window shows the contents in colorful rectangle blocks.

Hover your mouse pointer over a block to display the file name and size at the bottom of the view window. You can move the selection from a file to one of the folders and vice-versa by changing the focus. Press Cmd + [ and Cmd + ] to move up and down in the file hierarchy.

Click a block to lock the selection. Then, you can take action directly on that item. Press Space to take a quick look and click the Reveal button to show the selected file/folder in Finder.

What Makes GrandPerspective Unique?

  • You can change the sorting criteria by creation date, extension, file type, or folder and even choose a different color palette.
  • Select from the list of recently scanned folders to save time. Or select Load Scan Data to create a new view with older scanned data.
  • Create new filters for refining the view and perform filter tests to mix them in different ways. You can choose from audio, hard-links, images, app package contents, and more.
  • The app lets you rescan a folder with different settings. Afterward, open those results in a separate window to compare with the last results.

Download: GrandPerspective (Free)

2. OmniDiskSweeper

sweep drive with omnidisksweeper

OmniDiskSweeper is another disk space analyzer for Mac. Upon launch, select a drive from the list and click Sweep Selected Drive. A new window opens with folders and files displayed in a column view. Once the scanning process completes, click on a folder and navigate to any file that takes up significant disk space.

The app uses different colors to group files by size and to show the status of an item. File sizes marked in green are the smallest files. As the size gets larger, this changes to dark green, dark purple, and light purple for huge files. Double-click on an item to open it in Finder.

What Does OmniDiskSweeper Offer?

  • It lets you sweep external and disk drives located on your network. If you share a folder located on a PC, the app can even scan that folder.
  • The bottom window provides you detailed information of a file, its size, and packages it belongs to in the file system. You should focus on files that are not part of packages.

Download: OmniDiskSweeper (Free)

3. Disk Inventory X

disk inventory multi faceted interface

Disk Inventory X is a utility app that gives you an overview of the space taken by different file types. Open the File menu and select any drive or a folder you would like to analyze. Once the scanning process finishes, the app creates a graphical treemap for visualizing storage space.

The left panel helps you sort the file list based on the colors associated with a particular file type, size, number of files, and file format. Click on any element in the graph to help you identify and locate the biggest files.

Unique Features of Disk Inventory X:

  • Any selection you make in the treemap graph gets synchronized with the finder-like view. This helps you find the major culprits, no matter where they are on the disk.
  • The app sorts file types in descending order. Each file type has a color used in the treemap graph and throughout all open folders.
  • You can view package contents, zoom into folders, and hide free space to analyze disk space in different ways.

Download: Disk Inventory X (Free)

4. DaisyDisk

DaisyDisk beautiful user interface

DaisyDisk is a beautifully designed disk analyzer that uses a sunburst map to show you a disk overview. Upon launch, it displays all mounted volumes with different color styles. Green means that at least half of your disk is empty, while red denotes that it’s time to take action.

Click the Scan button, and within a few seconds, you’ll see the map with a brief overview on the sidebar. Place your mouse over any segment to see its contents on the sidebar. When you want to navigate to the parent folder, click in the center of the disk map.

Key Features of DaisyDisk

  • The sunburst map helps you separate the huge files from smaller ones. Drill down and find out which items are consuming the most disk space.
  • If you scan the disk as an administrator, it can reveal more data about files hidden on other volumes, space taken by local snapshots, and details on purgeable space.
  • You can preview any file from the sidebar, send them to a collector panel, then delete them at your convenience.

Download: DaisyDisk ($9.99, free trial available)

5. NCDU

ncdu command-line disk space analyzer

NCDU is a command line disk analyzer with a ncurses interface. It’s based on the du command, but it’s much faster and easy to use on your Mac and remote servers. To get started, you’ll need to install the app through Homebrew. To do this, see how to install Mac apps using Homebrew How to Install Mac Apps in Terminal Using Homebrew Did you know you can install Mac software in the Terminal? Here's how to use Homebrew to install Mac apps easily. Read More .

Once installed, open Terminal and type in ncdu / to start scanning your drive. Use the arrow keys to navigate across items. Then, press i to view the details of the selected item.

Unique Features of NCDU

  • You can use different options to enhance the disk-related information. Navigate to the NCDU man page for more details.
  • It’s easy to export all the information to an output file. You can then use file comparison apps to better analyze your disk usage.

Download: NCDU (Free)

Stay on Top of Your Mac’s Free Space

Getting accurate details about free and used space on your Macis tricky. While there are many built-in techniques, most of them are unreliable for detailed use. Use Disk Utility and these apps to inspect and analyze your storage space in detail.

For more help, make sure to check our big list of tips for creating free space on your Mac How to Free Up Space on Mac: 8 Tips and Tricks You Need to Know Running out of storage space on your Mac? Here are several ways to free up space on Mac and reclaim your drive space! Read More .

Explore more about: Computer Maintenance, File Management, Hard Drive, Mac Apps, Mac Tips, Solid State Drive, Storage.

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  1. keerry
    May 7, 2018 at 2:39 am

    to analyze the disk space of mac, i think dr.cleaner is also a very useful sofeware which could satisfy your requirements.

  2. kirk
    April 18, 2018 at 3:58 pm

    What about something that sends a notification on exceeding the high water mark for storage use? These tools are fine for maintenance, but are reactive. Something that would proactively notify the user of impending doom, would be really useful.

  3. Deezy
    January 22, 2017 at 4:06 pm

    Regarding JDiskReport - some of us still need Java for other reasons (I run an older, non-subscription version of Photoshop that requires it) so I didn't write this option off as quickly as you did.

    As far as the value of the utility itself....

  4. Filmberichte
    March 7, 2010 at 5:31 pm

    Thanks for the article, it was very helpfull.

  5. broit
    December 28, 2009 at 7:37 am

    I use ONYX for many years, from 10.4, than 10.5 and now 10.6 and must admit I can always keep my HD fit and mean. Whenever I feel it overloaded or slumpimg, I give him a brush up with ONYX different tools onboard, and it helps dramatically

  6. Justin
    December 20, 2009 at 11:48 am

    Sean: Snow Leopard reveals sizes when you use List View (View ... as List or CMD+2). It basically makes the "Calculate all sizes" option obsolete.

  7. Sean
    December 11, 2009 at 9:17 pm

    Which OSX are you using? I can't seem to find the option that says "Calculate all sizes." Maybe its a Snow Leopard only thing (that is, if you are using Snow Leopard) or you modified something else?

  8. Paf
    December 10, 2009 at 6:16 pm
  9. Glenn C.
    December 10, 2009 at 1:15 pm

    There's also DaisyDisk [mac]: http://www.daisydiskapp.com/
    with a colorful, sunburst visualization style.

  10. Glenn C.
    December 10, 2009 at 1:11 pm

    There's also DaisyDisk [mac]: http://www.daisydiskapp.com/
    with a colorful, sunburst visualization style.