WizTree for Windows: Find what’s taking up disk space

When Windows says a drive is nearly full, the immediate question is where the space went. The answer may be an old video project, a game you forgot you installed, or a stack of installers in Downloads. WizTree scans a drive and shows which folders and files account for the space. You can use that information to decide what to move, uninstall, or leave alone.

Antibody Software, the developer, provides WizTree for Windows free for personal use. Commercial use has separate licensing terms. The steps below work best if you start with a specific drive, look for files you recognize, and verify what Windows reports after any cleanup.

Run your first scan

Get the installer or portable edition from the developer’s website. The portable edition is useful if you want to run the program without a normal installation. On a work PC, use your organization’s approved software process and check the licensing terms before running either edition.

1. Open File Explorer and check which drive is low on space. On many PCs the system drive is C:, but an external drive or secondary SSD can fill up independently.
2. Open WizTree, select the drive, and choose Scan. Wait for the folder and file results before choosing what to inspect.
3. Open the largest folder branches and follow them until the paths make sense. If a folder is unfamiliar, stop there and identify the application or Windows component that owns it.
4. Use the file list to find large individual items. The folder tree is better for spotting many smaller files that add up, such as an archive of exported images.

WizTree can read the Master File Table directly when it scans NTFS. The Master File Table is where that file system keeps records about files and directories. According to the developer, this faster scan mode needs administrator rights. WizTree can also scan other file systems and network drives, so the scan method and time can differ between drives.

Read the treemap before opening folders

The treemap turns the scan results into rectangles. Area tells you which items take up more space in the current view. If one block dominates the map, start by checking its file path. If the map is a collection of medium-sized blocks, the folder tree can help you see whether they belong to a single project or several unrelated locations.

Suppose you see a large block for a project folder. Expand it and check whether the space belongs to source footage, generated previews, or a finished export. Moving a backed-up export and deleting the source footage have very different consequences. A filename and size tell you where to look. The full path and the application that created it help you decide what to do.

Compare Size and Allocated

The Size column shows the file’s logical length. Allocated shows the disk space reserved to store it. Drives assign storage in units called clusters, so a small file can occupy more disk space than its contents alone would suggest. A compressed file may show the opposite pattern. The difference matters when you are trying to reclaim space on the drive you scanned.

The total may differ slightly from the used-space figure in Windows. WizTree’s FAQ explains that NTFS stores information such as directory indexes and file security data. Some of that data takes space without appearing as ordinary files in the scan. A small difference is therefore a poor reason to start deleting hidden folders.

Choose a cleanup action that fits the file

Start with files you own and can identify. Look for an installer you can download again, a video you already exported and backed up, or a duplicate archive whose contents you can compare. For anything you intend to keep, copy it to the new location and confirm that it opens there before deleting the original. If the only copy is on the drive you are cleaning, make a backup first.

Use Windows Settings or the software’s own launcher to uninstall an application or game. Removing its folder by hand can leave the installation in an inconsistent state. For application caches, use the app’s settings when it has a cleanup option. This is especially useful for editing tools that can rebuild previews but may keep originals in a nearby folder.

Windows system folders and folders under Program Files or AppData can contain files the operating system or an app needs. A large number in the scan does not tell you whether a file is safe to remove. If you want to review temporary files, open the Storage settings in Windows and read the categories it offers before confirming any deletion. Check Downloads and the Recycle Bin separately if you still need files from those locations.

Check that the cleanup freed space

Rescan the drive after moving or removing a batch of files and compare the free-space figure in Windows. If you moved something to a different folder on the same drive, the drive still stores the data. Files sitting in the Recycle Bin can also continue to use space. Review the bin’s contents before emptying it, particularly if you removed several items in a hurry.

If the drive fills up again, compare the biggest branches between scans. A growing folder can be more informative than the largest folder on a single day. For example, a stable collection of photos might account for much of the drive while a rapidly growing export folder is responsible for the new space warning. Track the folder that changes and check the app’s storage settings.

If you are retiring the drive itself, file cleanup is a separate task from preparing it for reuse. Shifted Magazine’s guide to wiping a hard drive for reuse covers the separate process of erasing the drive. Back up anything you need before considering that step.

A scan of an external drive can be easier to read if you start with the folder you actually use for backups. Old backup sets can look alike and still contain different recovery points. If backup software created them, open that software to review its retention settings before removing a set. For an ordinary folder of copies, open a few files and compare the dates and paths before deciding which copy to keep.

You can also write down the free-space figure before each cleanup. That gives you a practical check on what changed, especially when you move several items and cannot remember how large each one was.

Common questions about WizTree

Is WizTree free?

Yes, for personal use under the developer’s terms. A business should check Antibody Software’s commercial licensing options before using it on company computers.

Can I use it on a drive other than C:?

Yes. Choose the drive you want to investigate in the scan selector. If it uses a file system other than NTFS, it will not use the same direct NTFS scan method.

Does a scan delete anything?

Scanning reads and displays the results. Cleanup is a separate decision. If an item looks unfamiliar, use its path to identify it before taking action.