Windows PC Out of Disk Space: Find What Is Using It

October 25, 2026 · iFixediT! Team · 5 min read

A full drive causes slow starts, failed updates and programs that refuse to save files. The good news is that most of the space is usually taken by a handful of things, and you can find them in about ten minutes of looking.

This guide is written for Windows 10 and Windows 11. Where a Mac works differently, there is a note.

Step 1: See how full the drive really is

Open File Explorer, click This PC, and look at the bar under your C: drive. If it is nearly full, keep going. A drive that is fuller than you expected is the signal to look for what is taking the space, not to start deleting at random.

On a Mac, click the Apple menu, choose System Settings, then General, then Storage. You will see a colored bar showing what kinds of files use the space.

Step 2: Let Windows show you the biggest categories

Windows has a built-in storage report. Open Settings, choose System, then Storage. After a moment you will see a breakdown such as Apps and features, Temporary files, Documents, Pictures and Videos.

Click any category to see details. This is the safest way to start because Windows only shows you things it understands. Look for the largest item first. Often it is one of these:

Apps and games you no longer use
Temporary files
A Downloads folder that has not been emptied in years
Videos and photos
Old Windows update files

On a Mac, the Storage screen lists the same sort of categories, and each has an information button that opens a list of files you can review.

Step 3: Clear temporary files

Temporary files are leftovers from programs and updates. They are meant to be disposable.

In Settings, go to System, then Storage, then Temporary files. Windows lists what it can remove and ticks the safe items for you. Typical entries include the Recycle Bin, Downloads, thumbnails and temporary files.

Read the list before you click Remove files. The Downloads entry deserves a pause: it will delete everything in your Downloads folder, so open that folder first and move anything you want to keep. The Recycle Bin entry is permanent too, so glance inside it before emptying.

An older tool called Disk Cleanup is still on many PCs. Search the Start menu for it, pick your C: drive, and tick the categories you want to clear. Disk Cleanup also has a button called Clean up system files, which can remove old copies of Windows update files. This often frees a noticeable amount of space on a PC that has been updated for years.

Step 4: Remove programs you do not use

Go to Settings, then Apps, then Installed apps. You can sort the list by size using the sort option near the top. Scan for programs you do not recognize as useful, or trial software that came with the PC.

Only remove things you know you do not need. If a name is unfamiliar, search for it before deciding. Some entries are drivers or components that your hardware needs, and removing them can cause problems. When in doubt, leave it alone.

On a Mac, open the Applications folder in Finder, drag an unwanted app to the Trash, then empty the Trash. Some apps also leave files elsewhere, but those are usually small.

Step 5: Hunt down large files yourself

If the categories do not explain where the space went, look for big files directly. In File Explorer, click the search box in the top right, type size:gigantic, and press Enter. Windows lists files larger than 128 megabytes. You can also try size:huge for files between 16 and 128 megabytes.

Right-click the results column header, choose Size if it is not showing, and sort from largest to smallest. Common finds are old video recordings, disk images, installer files you downloaded once, and backup copies of phones.

On a Mac, open Finder, press Command and F, then change the search criteria to File Size and set a minimum, for example larger than 500 megabytes. Sort the results by size.

Before deleting any large file, ask yourself whether it exists anywhere else. If it is a family video or a business document and this is the only copy, copy it to an external drive or a cloud storage service first.

Step 6: Move things instead of deleting them

You do not have to delete photos and videos to free space. Copying them to an external hard drive, then deleting them from the PC once you have confirmed the copy opens, is a safe approach. Cloud storage works too, as long as you check that the upload has finished.

A good habit is to open a few of the copied files on the new location before removing the originals from the PC.

What not to delete

Some folders look large and tempting but should be left alone:

The Windows folder
Program Files and Program Files (x86)
The hidden folder called WinSxS, which Windows manages itself
The file named hiberfil.sys or pagefile.sys, unless you know exactly why you are changing them

If a file or folder is not yours and you are not sure what it does, leave it. Windows tools such as Storage settings and Disk Cleanup are designed to remove only what is safe.

Keep it from filling up again

Once you have cleared space, a few small habits help. Empty the Downloads folder every few months. Turn on Storage Sense in Settings, under System, then Storage. It can clear temporary files and old Recycle Bin items on a schedule you choose. Keep photos and videos on an external drive or in the cloud instead of only on the PC.

If you have cleaned up and the drive is still almost full, or you are not sure whether a file is safe to remove, it is reasonable to stop and ask someone you trust to look at the screen with you. A full drive is easy to fix, but careless deleting is hard to undo.

If you would rather not do this alone, iFixediT can help: Fixie, our AI helper, answers first, and people help on paid plans.