Disk Space Analyzers for Windows and Mac, Ranked by Scan Speed

Windows told me my drive was full. I opened Settings > System > Storage and got a pie chart that said “Temporary files: 42GB” and basically nothing else. That vague overview is what pushed me into disk space analyzers in the first place, and the rabbit hole turned out to be deeper than I expected. Some of these tools finish a scan of a 512GB SSD before you can blink. Others sit there crawling folder by folder for 20 minutes. The gap comes down to how each one reads the drive under the hood.

Here is what I found after running a handful of them on the same machine: an old ThinkPad with a 512GB SSD, around 300,000 files, and the usual pile of forgotten downloads, old movies and half-played games.

The MFT trick that makes WizTree so fast

WizTree from Antibody Software Limited is the speed outlier here. I scanned my C: drive and the whole thing took 1.42 seconds. The app shows a timer after each scan, so that number is not something I rounded down for effect.

How does it get there? It reads the NTFS Master File Table directly from disk instead of walking the file system one folder at a time. The MFT already knows about every file and folder on an NTFS volume, so the tool skips the slow crawl entirely. Same basic mechanism the Everything search app from voidtools uses. Once you have watched that, waiting on a traditional analyzer feels like watching paint dry.

What WizTree actually supports

• NTFS, exFAT and FAT32 drives
• Network drives
• MTP/PTP devices, so an Android phone or a camera connected over USB can be scanned too

The treemap is the part I keep coming back to. Large files become big blocks, and you spot them without reading file names. I found a video I had completely forgotten about just by staring at the layout for a few seconds. Right-clicking a block lets me rename the file, copy its path or delete it without leaving the app.

Careful with that last one. A big Windows folder showing up as a chunky block does not mean it is safe to delete. System files and application data live in there and Windows will not thank you. The tool is happy to remove anything you point it at, which is convenient and slightly dangerous at the same time.

Price and limits

WizTree is free for personal use, with a business license if you need one. The catch is platform support: it is Windows only. On a Mac you are looking elsewhere, and the alternatives trade some raw speed for cross-platform coverage.

Where the other analyzers land

Traditional disk space analyzers crawl the file system folder by folder. That is the polite way of saying they open each directory, read what is in it, add up the sizes and move on. On 300,000 files that adds up to minutes, not seconds. On a spinning drive with lots of small files, longer.

The trade-off is not one-sided. Tools that do not depend on the NTFS Master File Table generally work the same way on APFS, HFS+, ext4 and network shares. If you are dealing with a Mac, a NAS, or a Windows machine formatted with something unusual, the MFT shortcut is not available anyway.

Mac side: what changes

APFS does not expose an equivalent to the Windows MFT in the same way, so none of the Mac analyzers hit WizTree numbers. The good ones still scan a 512GB Mac drive in a couple of minutes if the drive is healthy and not encrypted with something odd. The bad ones take 10 minutes or more and lock up the UI while they work.

If you are on a Mac, look for two things: a native ARM build so it does not run under Rosetta, and a scan that reports progress while it runs. A frozen progress bar is the tell that the app is doing blocking I/O on the main thread. That is a sign the developer did not think hard about the scanning part, and it usually means the rest of the app is rough too.

Reading the results without breaking Windows

Every analyzer will happily highlight folders you should not touch:

• WinSxS: the Windows component store. It looks enormous. Deleting from it breaks updates and sometimes the OS.
• System Volume Information: restore points and shadow copies. Windows manages the size for you.
• ProgramData: shared app data. Often safe to leave alone, occasionally huge because one app is hoarding cache.
• AppData\Local: browser caches, Electron app caches, game shader caches. This is usually where the real savings live.

Browsers and chat apps are the biggest repeat offenders. Spotify, Slack, Discord and Chrome all build multi-gigabyte caches that nobody cleans manually. WizTree users usually spot the offender within a minute of opening the treemap. Deleting the cache folder while the app is closed is safe in almost every case. Deleting it while the app is running is a good way to corrupt something.

Windows Storage settings vs a real analyzer

Windows 11’s built-in Storage page is fine for a glance. It tells you Temporary files are eating 40GB. It does not tell you which files. That is the exact piece of information you need when the SSD is genuinely full and you have five minutes before a meeting.

The same gap applies to Microsoft PC Manager, which Microsoft promotes for clearing storage and managing startup apps. It is a decent cleanup tool, but it is not an analyzer. It sweeps known clutter categories. It will not show you that one forgotten 18GB video render sitting in a project folder from 2023.

Speed versus reality

WizTree changed how often I actually bother scanning. At 1.42 seconds per scan, I do it on a whim. Tools that take five minutes make me schedule the task mentally, and then I never do it. That behavioural difference matters more than raw benchmark numbers, because an analyzer you avoid using is worth nothing.

If you are on Windows with NTFS drives, the ranking is not close. WizTree first. Everything else is a distant second unless you need a feature it does not have, such as a specific export format or a network deployment license.

Who should skip WizTree

• Mac users, since there is no Mac build. Look for a native APFS-aware analyzer instead.
• Anyone scanning exclusively non-NTFS volumes where the MFT fast path does not apply. The speed advantage shrinks.
• People who want an all in one disk cleaner with one-click cleanup. WizTree shows you the problem and helps you delete, but it does not automate the cleanup decisions.

Who should install it today

• Windows users with a full or nearly full SSD who want to know exactly what is eating space.
• Anyone running an old PC with a spinning drive, where the speed difference versus traditional analyzers is even more dramatic.
• People who plug in Android phones or cameras and want to see what is on them without copying files first.

One piece of advice before you delete anything: take a screenshot of the treemap after the scan. If you remove something and an app stops working, that screenshot is the only record of what used to be there. WizTree does not have a built-in undo. Neither does Windows.

Download it from Antibody Software’s own site. The installer is small, the free version covers personal use, and the scan takes less time than reading the license screen.