Where’s My Disk Space Going?

Our disk drive is split into a C: and a D: drive. We only ever save on the D: drive, but the C: drive has only about 540MB left available! Apart from about 5GB of photos, I can’t understand what is taking up all the memory. The memory seems to continually go down and is now getting to a critical level. I have run malware checks and deleted all critical errors, but still not been able to free up any memory. I can’t even defrag as I need 20% free to run this option.

Disappearing disk space is a very common scenario.

Somehow, no matter how much we have, disk space never seems enough. As we collect pictures and programs (and the programs themselves collect data), more and more disk space is consumed. With so much happening on our computers these days, it’s difficult to understand what’s taking up space.

Fortunately, I can recommend a free tool that can give us some very helpful data.

TreeSize Free

TreeSize Free is a free tool that shows you what’s taking up all of the space on your machine. (A paid version is available with additional features, but for what we’re doing, the free version will suffice.)

Treesize Free
TreeSize Free (click for larger image).

Download TreeSize Free from the JAM Software page and install it.

On completion of the installation, you’re given the option to run it, or run it as Administrator.

Treesize Setup Complete
TreeSize setup complete.

I recommend you run it as Administrator so TreeSize can access and return as much information as possible about your hard-disk usage.

As TreeSize scans your hard drive, it updates its display in real time.

Once the small blue progress bar disappears, the results are complete.

Treesize Progress
TreeSize progress.

A typical machine

This is the result of running TreeSize on C:\ of a basic Windows 10 installation.

Treesize Results
TreeSize results (click for larger image).

The primary information here is a list of all of the top-level folders on the C: drive with the amount of disk space they consume. It’s sorted by decreasing disk space, so the biggest space-consumers are at the top.

Not surprisingly, it shows that the “Windows” folder and everything it contains consumes the most space.

Digging deeper

You can see the contents of the next level of folders by clicking the small greater-than sign to the left of the folder name. Here’s the Windows folder expanded:

Treesize Windows
TreeSize Windows folder (click for larger image).

You can see right away that the “WinSxS” folder contains the most data of all the subfolders within C:\Windows. (This is normal, by the way.) You can also see the relative size of each of the other folders within Windows. If you want to drill down deeper, keep expanding subfolders.

TreeSize on user files

It’s useful to see what’s stored in your user account’s folders. In Windows, that means looking at the contents of “C:\Users\<login name>.” In my case, that’s C:\Users\lnote.

Treesize User
Treesize user account folder (click for larger image).

You can see that AppData and its contents take up the most space in my account, with the Evernote folder being next.

Your machine

Now, as to what’s eating up the disk space on your machine, there’s no way for me to know. However, using a tool like TreeSize, you should be able to see what’s taking up all that space and take appropriate action.

Aside: Disk space is not memory

People confuse these terms a lot, and it’s very important — particularly when asking for help — that the terms you use accurately reflect what you’re talking about. To oversimplify a little:

  • Memory is the RAM (Random Access Memory) in which your programs and data reside when they are in use. When you turn your computer off, your memory is erased. To free up memory, run fewer programs at the same time.
  • Disk space is about your hard drive, where data is stored permanently (or until you or a program explicitly erases it). To free up disk space, delete files.

Another good difference to note is size. My laptop, for example, has 16 gigabytes of memory, but a terabyte (1024 gigabytes) of disk space. Disk space on a machine is almost always much greater than its RAM.

Video Narration


: Yes, this does make the ironic assumption that you have enough space to download and install the tool. Fortunately, it’s not large.

Originally published as Where’s My Disk Space Going? on Ask Leo!