8 Best Free Disk Space Analyzer Tools

Free software for finding the largest files on a hard drive

Ever wonder what's taking up all that hard drive space? A disk space analyzer tool, sometimes called a storage analyzer, tells you the details.

These programs scan and interpret everything that's using up disk space, like saved files, videos, program installation files—everything—and then provide you one or more reports that help make very clear what's using up all your storage space.

Person searching through literal file cabinets on a laptop for extra disk space
Lifewire / Nez Riaz

If your hard drive (or flash drive, or external drive, etc.) is filling up, and you're not exactly sure why, one of these completely free disk space analyzer tools should really come in handy.

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Disk Savvy

Disk Savvy v13 in Windows 10
What We Like
  • Much easier to use than most disk space analyzers

  • Categorizes files in several ways

  • Updates to newer versions often

  • Able to scan multiple locations simultaneously

  • Results can be exported to a report file

  • Also works from within Explorer

What We Don't Like
  • Not all features you see in the program are free to use; some require you to upgrade to the Pro edition

  • It can show only 500,000 files per scan

We list Disk Savvy as the No. 1 disk space analyzer program because it's both easy to use and full of useful features that are sure to help you free up disk space.

Analyze internal and external hard drives, search through the results, delete files from within the program, and group files by extension to see which file types are using the most storage.

Examine a list of the top 100 biggest files or folders. You can even export the list to your computer to review them later.

There's a professional version of Disk Savvy available, too, but the freeware version seems perfect. Install Disk Savvy on Windows 10 through Windows XP, as well as on Windows Server 2016/2012/2008/2003.

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WinDirStat in Windows 8
What We Like
  • Scan a whole drive or a single folder

  • Provides unique ways to visualize disk space

  • Includes the option to configure commands to delete data

What We Don't Like
  • Unable to save the scan results to a file that you can reopen later

  • A bit slower at scanning than similar tools

  • Runs on Windows only

WinDirStat ranks right up there with Disk Savvy in terms of features—we're just not too fond of its graphics.

Create your own custom cleanup commands. These commands can be used from within the software at any time to do things quickly, like move files off the hard drive or delete files of a certain extension that are in the folder you select.

You can also scan different hard drives and folders all at the same time as well as see which file types are using up the most space, both of which are unique features not found in all of these disk usage analyzers.

Install WinDirStat in the Windows operating system only.

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JDiskReport v1.4.1 in Windows 8
What We Like
  • Shows disk space usage in five different perspectives

  • Really easy to understand, even for new users

  • Works on Linux, Windows, and macOS

What We Don't Like
  • Doesn't let you delete files from within the results

  • Noticeably slower than other disk space analyzers

Another free disk space analyzer, JDiskReport, shows how files are using storage through either a list view like you're used to in Windows Explorer, a pie chart, or a bar graph.

A visual take on disk usage helps you understand how the files and folders behave in relation to the available space.

One side of the JDiskReport program is where you find the folders that were scanned, while the right side provides ways to analyze that data.

You cannot delete files from within the program, and the time it takes to scan a hard drive seems slower than some of the other applications in this list.

Windows, Linux, and Mac users can use JDiskReport.

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TreeSize Free

TreeSize Free v4.0.0 in Windows 8
What We Like
  • Lets you remove files from within the program

  • Can scan individual folders and entire hard drives

  • Supports both internal and external HDDs

  • There's a portable option available

What We Don't Like
  • Doesn't work on Linux or macOS

  • Filtering options aren't super helpful

  • No unique perspectives are available like there are with similar tools

The programs mentioned above are useful in different ways because they provide a unique perspective for you to look at the data. TreeSize Free isn't so helpful in that sense, but it certainly provides a feature that's missing in Windows Explorer.

Without a program like TreeSize Free, you really don't have an easy way to see which files and folders are occupying all the disk space. After installing this program, seeing which folders are largest and which files among them are using up most of the space, is as easy as opening the folders.

If you find some folders or files that you no longer want, delete them from within the program to free up that space.

Get a portable version that runs on external hard drives, flash drives, etc. without installing it to the computer. Only Windows can run TreeSize Free. 

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RidNacs v2.0.3 in Windows 10
What We Like
  • Minimal and simple interface makes the program easy to use

  • There's a portable option

  • Supports scanning for large files in a specific folder or the whole drive

What We Don't Like
  • Won't run on Linux or macOS

  • Missing advanced features found in similar applications

RidNacs is for the Windows OS and is similar to TreeSize Free, but just doesn't have all the buttons that may drive you away from using it. Its clear and simple design makes it more appealing to use.

Scan a single folder with RidNacs as well as whole hard drives. This is an important feature in a disk analyzer program because scanning an entire hard drive may take a long time when you really just need to see the info for one folder.

RidNacs' functionality is straightforward so you know exactly how to use it right from the start. Just open the folders like you would in Windows Explorer to see the largest folders/files listed from the top down.

RidNacs just includes the basic features necessary for what a disk analyzer should have, but it lacks the features you'd find in a more advanced program like WinDirStat from above.

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Disktective v6.0 in Windows 8
What We Like
  • It's portable

  • Able to scan for large files in a specific folder or the whole hard drive

  • Provides two ways to view the disk space usage

  • Lets you export the results to a file

What We Don't Like
  • Unable to delete directly from the program

  • Exported results are hard to read

  • The way size units are displayed makes reading the results hard

  • Only Windows users can install it

  • An update hasn't been released since 2010

Disktective is another free disk space analyzer for Windows. This one is completely portable and takes up less than 1 MB of disk space, so you can easily carry it with you on a flash drive.

Each time Disktective opens, it asks what directory you want to scan. You can pick from any folder on any hard drive that's plugged in, including removable ones, as well as the entire hard drives themselves.

The left side of the program shows the folder and file sizes in the familiar Windows Explorer-like display, while the right side displays a pie chart so you can visualize each folder's disk usage.

Disktective is easy enough to use for anybody, but it's hindered by a few key limitations: The export-to-HTML feature doesn't produce a very easy-to-read file, you can't delete or open folders/files from within the program, and the size units are static, meaning they're all either in bytes, kilobytes, or megabytes (whatever you choose).

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SpaceSniffer v1.3 in Windows 8
What We Like
  • Shows data usage with simple blocks

  • The results can be filtered a number of ways

  • Results can be backed up to a file and opened again without having to re-scan

  • Lets you delete files from inside the program

  • A report of the large files can be saved to a text file

  • Completely portable

What We Don't Like
  • Can be hard to grasp at first

  • Works on the Windows operating system only

Most of us are used to viewing the data on our computers in a list view where we open folders to see the files inside. SpaceSniffer works similarly but not in the same way, so it may take some getting used to before you're comfortable with it. It uses blocks of varying sizes to demonstrate larger folders/files versus smaller ones, where the brown boxes are folders and the blue ones are files (you can change those colors).

The program lets you export the results to a TXT file or a SpaceSniffer Snapshot file so that you can load it up on a different computer or at a later time and see all the same results—this is really handy if you're helping someone else analyze their data.

Right-clicking any folder or file in SpaceSniffer opens the same menu that you see in Windows Explorer, meaning you can copy, delete, etc. The filter feature lets you search through the results by file type, size, and/or date.

We've added SpaceSniffer to this list because it's different from the majority of these other disk space analyzers, so you may find that its unique perspective aids in helping you quickly find what's using up all the storage space.

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Folder Size

Folder Size v2.6 in Windows 10
What We Like
  • Integrates with Explorer

  • Lets you sort folders by size

  • Extremely easy to use

What We Don't Like
  • Shows results in an extra window instead of within the original window you're viewing

  • Runs on Windows only

Folder Size is the simplest program from this entire list, and that's because it has virtually no interface.

This disk space analyzer is useful because Windows Explorer doesn't provide you with the size of a folder you're looking at, but instead just the size of files. With Folder Size, a small additional window displays that shows each folder's size.

In this window, you sort the folders by size to easily see which ones are using the biggest slice of storage. The settings let you disable it for CD/DVD drives, removable storage, or network shares.

The screenshot above demonstrates that it's nothing like the other software from this list. If you don't need charts, filters, and advanced features, but just want to be able to sort folders by their size, then this program will do just fine.

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