The Windows built-in Storage settings screen shows you six pie slices and calls it a day. It will not tell you that a Steam game shipped 40 GB of unused DLC video, that Docker put 60 GB into a WSL VHD you never mount, or that Chrome’s cache in one profile grew to 12 GB. A proper disk space analyzer answers those questions in a minute.
We tested seven Windows disk space analyzers, from the treemap classics to the modern MFT-reading tools that scan a full SSD in seconds. Every pick works on Windows 10 and 11 and shows you what actually takes the space, not what Microsoft would like to categorise.
What to look for in a disk space analyzer
- Scan speed. Modern tools read the MFT directly and finish in seconds; older tools walk the filesystem.
- Treemap. A visual layout beats a nested list for finding the biggest culprits.
- File type filters. Groupings by extension or category catch caches and archives fast.
- Deletion from within the app. Cleaning up should not need a second Explorer window.
- Portable version. USB toolkits benefit from single-exe apps.
- Support for network paths and mapped drives. Not every big folder lives on C:.
Quick comparison
| App | Best for | Platforms | Free plan | Starting price | Rating |
|---|---|---|---|---|---|
| WinDirStat | The classic open-source treemap | Windows | Yes | Free | 4.6 |
| WizTree | The fastest MFT-based scanner | Windows | Yes | Pro $30 one-time | 4.9 |
| TreeSize Free | The polished free scanner | Windows | Yes | TreeSize Pro from $56 | 4.7 |
| SpaceSniffer | The single-exe portable classic | Windows | Yes | Free | 4.6 |
| RidNacs | Fastest of the “list view” scanners | Windows | Yes | Free | 4.5 |
| Scanner | Concentric sunburst view | Windows | Yes | Free | 4.4 |
| GetFolderSize | Reports and CSV exports | Windows | Yes | Free | 4.4 |
| TreeSize Professional | Enterprise-grade with scheduled scans | Windows | 30-day trial | ~$56 one-time | 4.8 |
The apps
1. WinDirStat – Best free treemap
WinDirStat is the app most Windows users think of when someone says “disk space analyzer.” It walks the filesystem, builds a treemap, and colours files by type. The 2024 branch (WinDirStat Next) added a proper multi-threaded scan and Windows 11 UI polish that the original desperately needed.
Where it falls short: Slower than WizTree because it walks the tree rather than reading MFT. A 4 TB drive can take five to ten minutes.
Pricing: Free, open source.
Platforms: Windows.
Download: WinDirStat, WinDirStat Next on GitHub
Bottom line: Everyone’s first pick. Still worth installing even when you have WizTree next to it.
2. WizTree – Best fastest scanner
WizTree reads the NTFS Master File Table directly. A full 2 TB drive scans in five to fifteen seconds. That speed changes how you use the app: run it before every big cleanup instead of “when things feel slow.”
Where it falls short: Requires an NTFS volume. Network drives fall back to a slower scan mode. Advanced features (file finder, custom exports) are behind the paid tier.
Pricing: Free for personal use. Pro $30 one-time for commercial and advanced features.
Platforms: Windows.
Download: WizTree
Bottom line: The pick that changes disk analysis from a chore into a one-minute check-in.
3. TreeSize Free – Best polished free scanner
TreeSize Free is the free tier of JAM Software’s paid TreeSize Professional. The free build handles per-file breakdowns, treemaps in newer versions, and Explorer context-menu integration. Right-click any folder and pick TreeSize to skip the app launch.
Where it falls short: Free lacks scheduled scans, network scans, and duplicate finder; those are Pro features.
Pricing: Free. Pro from about $56 one-time.
Platforms: Windows.
Download: TreeSize Free
Bottom line: The pick when the tool sits in a right-click menu and comes out ready to go.
4. SpaceSniffer – Best portable single-exe
SpaceSniffer is a single 1.5 MB executable. Drop it on a USB stick and it runs on any Windows machine. The treemap view is animated: files re-lay out as scans progress, which sounds fluffy and is actually useful for spotting new cache balloons in real time.
Where it falls short: Development is essentially dormant. It still works fine because the design was solid.
Pricing: Free.
Platforms: Windows.
Download: SpaceSniffer
Bottom line: Best pick for a portable IT toolkit where install is not an option.
5. RidNacs – Best minimalist list scanner
RidNacs skips the treemap and shows a fast, sortable list of folders by size, with in-line progress bars. For “which folder took the space?” it is the most direct tool on the list.
Where it falls short: No treemap. No visual layout. If you like pretty pictures, this is not it.
Pricing: Free.
Platforms: Windows.
Download: Splashsoft RidNacs
Bottom line: Best pick when you want raw numbers, not a picture.
6. Scanner – Best sunburst view
Scanner shows the same data as WinDirStat in a concentric ring instead of a treemap. Each ring is a folder depth. Click a slice to zoom in. Old-school, fast, and satisfying.
Where it falls short: Not maintained in recent years. UI does not scale for high-DPI screens; a manual tweak fixes it.
Pricing: Free.
Platforms: Windows.
Download: Steffen Gerlach’s site
Bottom line: The pick if you find treemaps hard to read and prefer the pie-chart metaphor.
7. GetFolderSize – Best for CSV exports and reports
GetFolderSize is the analyzer that shows up on IT team file shares. It exports full folder-size reports to CSV, prints, and PDF, and handles UNC paths to network shares.
Where it falls short: The interface has not changed in years. Aesthetics are utilitarian.
Pricing: Free.
Platforms: Windows.
Download: GetFolderSize
Bottom line: The best pick when the goal is “hand my boss a report,” not “clean my own drive.”
8. TreeSize Professional – Best enterprise-grade tool
TreeSize Professional is the paid TreeSize that turns the free tool into an audit system. Scheduled scans, historical trend charts, duplicate file finder, deep dive into archive contents, and Active Directory integration.
Where it falls short: Priced for teams. Overkill on a single personal machine.
Pricing: 30-day trial, then $56 one-time for a personal license.
Platforms: Windows.
Download: JAM Software TreeSize
Bottom line: The pick when disk analysis is part of the job, not a one-off cleanup.
How to pick the right one
- If you install one thing: WizTree for the speed, then WinDirStat for the treemap.
- If you want portable: SpaceSniffer.
- If you want a right-click menu entry: TreeSize Free.
- If you want raw lists: RidNacs.
- If you want a sunburst: Scanner.
- If you export reports: GetFolderSize or TreeSize Professional.
- Never install more than three of these. WizTree plus one visual scanner plus one for reports covers every real workflow.
FAQ
What is the fastest disk space analyzer for Windows?
WizTree, by a wide margin. It reads the MFT directly on NTFS volumes and finishes multi-terabyte scans in seconds.
Is WinDirStat still maintained?
Yes. The original is on a slow release cadence, but WinDirStat Next has active releases with performance and UI updates.
Which one shows duplicate files?
TreeSize Professional and dedicated duplicate finders. WinDirStat and WizTree focus on sizes, not duplication.
Do these tools work on Windows Server?
WinDirStat, WizTree, SpaceSniffer, and TreeSize all install on Windows Server. TreeSize Professional and GetFolderSize are the best picks for scheduled scans and reports on servers.
Are any of them safe on a work laptop?
All the free tools above are safe. They read the filesystem and (optionally) delete files you tell them to. None make silent changes.
