WizTree and WinDirStat are the two most popular free disk space analyzers for Windows. Both use a treemap to show you where your storage went, but they work very differently under the hood, and the gap between them has grown significantly.

Here's an honest comparison to help you pick the right one, plus a third option worth knowing about.

The short answer

WizTree is faster. WinDirStat is older. If you're on Windows and just need to find large files quickly, WizTree wins on speed. WinDirStat's main advantage is that it's open source and has been around longer, which some users trust more.

But neither runs on Mac. If that matters to you, keep reading to the end.

How they work

WizTree reads the Windows Master File Table (MFT) directly, a low-level structure on your NTFS drive that Windows uses to track every file. This lets it scan your entire drive in seconds without reading each file individually.

WinDirStat scans the traditional way: it walks through the file system directory by directory, reading each folder. This is more compatible (it works on any Windows file system, not just NTFS) but significantly slower.

Speed comparison

This is where WizTree wins decisively.

Drive Size	WizTree	WinDirStat
256 GB SSD	~5 seconds	2–4 minutes
1 TB HDD	~15 seconds	10–20 minutes
2 TB HDD	~30 seconds	20–40 minutes

For most users, the speed difference is dramatic enough to make WinDirStat feel unusable in comparison. On a large drive, WizTree finishes before WinDirStat even reaches 10%.

Visualization

Both tools use a treemap, the same concept where larger rectangles = larger files. Side by side they look similar, but there are differences:

WizTree's treemap:

Loads instantly (because the scan is so fast)
Color-coded by file type
Clicking navigates into folders

WinDirStat's treemap:

Loads progressively as the scan runs
Color-coded by file extension (same file type = same color)
The file list and treemap update together during scanning

WinDirStat's "live loading" treemap can be interesting to watch, but practically speaking WizTree's instant result is more useful.

Features

Feature	WizTree	WinDirStat
Scan speed	Very fast (MFT)	Slow (file-by-file)
File system support	NTFS only (fast)	Any Windows FS
Treemap	✅	✅
File type breakdown	✅	✅
Portable (no install)	✅	✅
Open source	❌	✅
Mac support	❌	❌
Price	Free	Free

When to use WizTree

You're on Windows with an NTFS drive (almost everyone)
You want the fastest possible scan
You need to find large files quickly and don't care about open source

WizTree is the better tool for most Windows users.

When to use WinDirStat

You need open source software (required by your organization's policy)
You're scanning a non-NTFS drive (FAT32, exFAT) where WizTree's speed advantage disappears
You prefer watching the treemap build live during the scan

WinDirStat is a capable tool, but for most everyday disk cleanup tasks, WizTree's speed makes it the winner.

The gap both tools share: no Mac support

Here's the thing neither WizTree nor WinDirStat solves: they're both Windows-only.

If you use Mac alongside Windows, or you switched to Mac and want the same kind of visual disk analysis, you need a different tool.

FreeUpDisk is built exactly for this. It uses the same treemap approach as WizTree and WinDirStat, scans fast on both Windows and Mac, and it's free.

Tool	Windows	Mac	Treemap	Speed	Price
WizTree	✅	❌	✅	Very fast	Free
WinDirStat	✅	❌	✅	Slow	Free
FreeUpDisk	✅	✅	✅	Fast	Free

Verdict

Pure Windows user who wants the best performance → WizTree
Need open source / non-NTFS drives → WinDirStat
Use both Windows and Mac, or Mac only → FreeUpDisk

WizTree beats WinDirStat on speed for almost every real-world use case. But if Mac support matters, neither of them solves your problem, and that's where FreeUpDisk comes in.

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