# Windows Disk Space Analyzer: see what fills your C drive

> A disk space analyzer for Windows 10 and 11 that shows any drive as an overview, treemap, sunburst, file types and folders, and explains the system folders before you clean.

Canonical: https://bytesweep.app/windows-disk-space-analyzer.html
Last updated: 2026-11-04

## What is filling my C drive?

Windows Settings says "System & reserved" and "Other" and leaves it there. Bytesweep for Windows maps the whole drive, names the folders Windows keeps for itself, and cleans the safe ones with an undo.

[Try it free for 3 days](https://bytesweep.app/download.html) [Buy · $29.99](https://bytesweep.app/pricing.html)

**Free to try for 3 days.** Cleaning needs a licence: $29.99 once per computer. No subscription. Runs offline.

- By [Shajeen Ahamed](https://bytesweep.app/about.html#author)
- Updated 4 November 2026

**Short answer**

On a full C drive the biggest folders are usually Windows Update downloads, the component store (WinSxS), Windows.old after an upgrade, the page and hibernation files, temp files and big downloads or games. A disk space analyzer such as Bytesweep, WizTree or WinDirStat shows which folder holds the space; then clean the safe parts, with DISM for WinSxS.

### How do I see what is using space on my C drive?

Pick a drive, or any folder with Choose a Folder, and Bytesweep scans it once. Overview splits it into system files, apps, your files, developer files and temp files. Treemap draws every folder as a block sized by what it holds, so one 40 GB game or virtual disk is impossible to miss. Sunburst shows how folders nest from the root outwards. File Types adds up space by kind (video, archives, disk images, installers), and Folders is the classic sorted list.

Every view goes down to the single file. You can also right-click any folder in File Explorer and choose to analyze it, find duplicates or large files in it, or clean it, without opening the app first.

- Overview and Folders for the first look
- Treemap and Sunburst to see where one folder is hiding inside another
- File Types for "what kind of thing is filling this"

### Which system folders fill a C drive?

The biggest folders on a full C drive are rarely yours. Bytesweep names them and says what removing each one changes: Windows Update downloads in `SoftwareDistribution\Download`, the Delivery Optimization cache, the component store in `WinSxS`, `Windows.old` and `$Windows.~BT` after an upgrade, crash dumps, temp folders and the thumbnail cache, browser caches and game launcher leftovers.

The component store is cleaned the supported way, through DISM, never by deleting files. For the background on each, see [why the C drive is full](https://bytesweep.app/answers/why-is-my-c-drive-full.html) and [whether WinSxS is safe to delete](https://bytesweep.app/answers/is-it-safe-to-delete-winsxs.html).

### How do I find large and duplicate files on Windows?

Large files lists the biggest and oldest files on the drive, which is where forgotten downloads, ISO images and exported videos turn up. Duplicates finds exact copies, compared in full, and similar photos, and lets you choose the copy that stays. Developer folders get their own list: `node_modules`, `bin` and `obj`, Rust and Maven `target`, Gradle builds and Python virtual environments in projects you have not touched for months.

### Can I undo a cleanup, and what cannot be undone?

Clean ticks only what is plainly safe, such as temp files, caches and update leftovers, and leaves anything that needs a look unticked. What it removes goes to a restore point on the same drive, so Undo puts it back for 7 days.

Three things cannot be put back, and the app says so before you confirm: emptying the Recycle Bin, component store cleanup through DISM, and uninstallers that belong to an app vendor.

### Is a free analyzer like WizTree or WinDirStat enough?

WizTree, WinDirStat and TreeSize Free are good, and free for personal use. WizTree is the fastest on NTFS because it reads the Master File Table directly. WinDirStat is open source and now has sunburst and flame views and a duplicate finder. TreeSize Free gives a size-sorted tree with a treemap. If a map is all you need, start with one of them.

Bytesweep is for the next step: knowing what the big folders are, cleaning the safe ones for you, and being able to undo it. It also runs on a Mac and on Linux. [Our alternatives pages](https://bytesweep.app/alternatives/) compare the free tools with each other in more detail.

### How do I get started on Windows?

Bytesweep for Windows (Bytesweep: PC Cleaner & Transfer) comes from the Microsoft Store, for Windows 10 and 11, 64-bit. Scanning and every view are free for 3 days; cleaning needs a licence bought on this site, $29.99 once per computer, no subscription.

- Install it from the Microsoft Store
- Pick the C drive and press Check Now
- Open Treemap or Folders to see what is using the space
- Open Clean, untick anything you want to keep, and press Clean. Undo brings it back within 7 days

### Bytesweep vs WizTree, WinDirStat and TreeSize Free

|  | Bytesweep | WizTree | WinDirStat | TreeSize Free | Windows Settings |
| --- | --- | --- | --- | --- | --- |
| Price | $29.99 once | Free personal; from $25 for work | Free, open source | Free, personal use only | Built in |
| Treemap | Yes | Yes | Yes | Yes | No |
| Sunburst | Yes | Not listed | Yes | Not listed | No |
| Space by file type | Yes | Yes | Yes | Not listed | Categories only |
| Explains system folders | Yes | No | No | No | Partly |
| Cleans for you | Yes | No | Cleanup commands | No | Cleanup recommendations |
| Undo after cleaning | 7 days, with exceptions | Not stated | Recycle Bin | Paid editions only | No |
| Duplicate finder | Yes, plus similar photos | Yes | Yes | Paid editions only | No |
| Mac and Linux too | Yes | Mac (WizTreeMac) | No | No | No |

### Questions

#### What is the best free disk space analyzer for Windows?

For speed on NTFS drives, WizTree, free for personal use. For an open-source tool with the most views, WinDirStat. Both are good. Bytesweep costs $29.99 once and is for people who also want each folder explained and cleaned with an undo.

#### Why does Windows show so much under System and reserved?

It includes the page file, the hibernation file, the component store (WinSxS), restore points and reserved storage for updates. Most of it can only be reduced through Windows settings or DISM, never by deleting files. Bytesweep shows each part and its size.

#### Does Bytesweep read the Master File Table like WizTree?

Bytesweep does not claim MFT-speed scanning. If raw scan speed on a huge drive is what matters most, WizTree is the specialist.

#### Can it scan external drives and network shares?

It scans any drive Windows shows, and any folder you choose. Its Drives page also keeps a searchable catalogue of external drives, so you can find a file on one that is not connected.

#### Does it send my file list anywhere?

No. The scan stays on your PC. There is no account and no telemetry; the only network use is the trial and licence check, update checks and the update sources you switch on.

### Sources

Read on 4 November 2026. If something here has changed, write to [support@bytesweep.app](mailto:support@bytesweep.app) and it will be corrected.

- [Microsoft Support: Free up drive space in Windows](https://support.microsoft.com/en-us/windows/free-up-drive-space-in-windows-85529ccb-c365-490d-b548-831022bc9b32)
- [Microsoft Learn: Clean up the WinSxS folder](https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/clean-up-the-winsxs-folder)
- [WizTree (Antibody Software)](https://diskanalyzer.com/)
- [WinDirStat](https://windirstat.net/)
- [TreeSize editions (JAM Software)](https://www.jam-software.com/treesize/editions.shtml)

### Keep reading

- [**Bytesweep for Windows**](https://bytesweep.app/windows.html)
- [**Why is my C drive full?**](https://bytesweep.app/answers/why-is-my-c-drive-full.html)
- [**WizTree, WinDirStat and TreeSize compared**](https://bytesweep.app/alternatives/)
- [**Duplicate file finder**](https://bytesweep.app/duplicate-file-finder.html)
- [**How Bytesweep decides what is safe**](https://bytesweep.app/how-it-works.html)

### Try Bytesweep free for 3 days.

Or [download it](https://bytesweep.app/download.html) and see what it finds first. Related: [Bytesweep Pro for Mac](https://bytesweep.app/mac.html), [Mac disk space analyzer](https://bytesweep.app/mac-disk-space-analyzer.html), [Linux](https://bytesweep.app/linux-disk-usage-analyzer.html), [Duplicate file finder](https://bytesweep.app/duplicate-file-finder.html).

[Buy a licence · $29.99](https://bytesweep.app/pricing.html)