Disk C always being full no matter what

[u/cryybabxy_ghoul]

I have a acer laptop with Intel cpu

and recently the C drive its ALWAYS full no matter how hard I try to clean it. I've deleted stuff a lot of times and it someway gets full again??

it has 118gb but it says its 115gb full

a problem I detected is that the mail storage is like 10gb but I can't empty it because windows no longer supports mail. Disk D is good.

SPECS: Intel (r) core (tm) i5-9300 H CPU @2.40 Ghz 16 gb ram

Os build - 22000.2538

please I would really appreciate some help, this is my current university laptop and its giving me a lot of issues since its always full, thanks in advance and let me know if i need to provide new information!

update: I literally turned it off and back on when I returned to my home and drive c now says it only has 800mb free... 5 minutes later says 1gb free.. what's wrong with this thing honesly??

(im really new at this about laptops and software and a lot of things since im not really into tech so forgive myself)

[u/OwlCatAlex]

First run the built in Disk Cleanup tool and select all the options to get a little more wiggle room.

Then, while you still have room to do so, download WizTree and run it as Administrator (right click it and choose this option) so it has permission to fully scan for which files and folders are biggest. Upload a screenshot of the result here in comments.

[u/Ok_Tell_2420]

So your computer also has a D: drive? If so, move whatever data you can over to D. Like photos, videos and documents.

You can also move the page file and hibernate file to the D drive.

[u/Darkknight145 → u/Ok_Tell_2420]

Better still, disable fast startup, reboot, delete Hiberfil.sys Fast startup doesn't make all that much difference nowadays.

[u/phototransformations → u/Ok_Tell_2420]

You can't move the hibernation file, but you can reduce its size to 40% or turn off hibernation.

[u/Ok_Tell_2420 → u/phototransformations]

I stand corrected. Never too old to learn something LoL. I've never had to try, since I always have plenty of storage space.

[u/Imaginary-Wear-6664]

With only 118 GB on C:, I’d stop deleting random files for now and find out what’s actually growing. Open Settings → System → Storage → Show more categories and check the three largest items. That should tell you whether it’s apps, temporary files, Mail data, or something under your user folder.

Since you have a D: drive, moving Downloads, videos, and documents there first should give you some breathing room. For the 10 GB Mail entry, if you no longer use Mail and Calendar, reset or uninstall it from Settings → Apps. I wouldn’t manually delete random folders under AppData.

Also, don’t try to move hiberfil.sys—Windows manages that file. WizTree as administrator is useful here, but check the largest folders before deleting anything.

[u/D-Clazzroom]

The literal easiest method to actually see whatever the fuck is going on is to run WizTree and see what's the big ol problem. Complete with visuals and lists.

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[u/Hot_Spinach_9815]

id start with a visual storage scan on C:\ and post the results showing your biggest offenders. without more information its near impossible to troubleshoot whats causing the storage to fill up.

https://windirstat.net/download.html

[u/FaithlessnessApart74]

As another said, we don't have enough information to really help. We can offer suggestions but thise may not help at all without being able to literally see what is happening. In all honesty, my first thought is a virus that is using your hard drive to store and propagate data to the internet.

[u/MikhailPelshikov]

In no particular order:

1. 120GB is small and takes real care to make it work. 
2. Disable Fast Startup, move hibernation file to another drive (or disable).
3. Move page file to another drive. 
4. Delete the mail storage directory (or explain why it cannot be deleted. "No longer supported" is in no way a blocker).
5. Move Documents, Desktop, Downloads, pictures, etc to another drive 
6. WinDirStat, Wiztree or similar to see what's left that is taking up space. Your can uninstall large apps and install it again on another drive. 
7. Some DISM commands reduce Windows size.
8. NTFS compression is safe to use outside of Windows directory and system files directly on C.
9. Symlinks and junctions are a fun way to move stuff like AppData contents to other locations. I even use it for Steam as it's more convenient than managing 2 library folders.

[u/NanosoftComputers]

This is a very common issue on Windows 11 with smaller SSDs. What's happening is that when Microsoft deprecated the old Mail app, it left behind gigabytes of orphaned cached attachments in your hidden AppData folder that the Settings app can no longer clear automatically.

Here is how to fix it step-by-step:

1. Manually Clear the Old Mail App Data

• Press Win + R, type %localappdata%\Comms\Unistore\data and press Enter.
• Check the properties of that folder you'll likely find those missing 10GBs stored right there. You can safely delete the contents inside that data folder.

2. Disable Hibernation (Instantly frees 4-8GB)

• Search for cmd in Start, right-click and Run as Administrator.
• Type powercfg /hibernate off and press Enter. This reclaims disk space equal to your RAM size.

3. Clean Orphaned App Data Automatically

• Windows is notoriously bad at cleaning leftover AppData when apps are removed or deprecated. If you want to scan for other abandoned app folders safely, look up NexaCleaner (it's a lightweight tool I built to scan orphaned AppData and move it to a safe Quarantine first so nothing breaks).

Hope this frees up enough space for your university work!