How to Low Disk Space on C Drive in Windows 10, 8, 7?

May 17, 2021

Sometimes, you may meet the low disk space issue on the system C drive, and then the C drive will show a red bar in Windows File Explorer. Don’t worry and here we will show how to extend the system drive or free up space on the drive to solve the low disk space problem in Windows 10, 8, 7.

Drive C shows red bar!

Many users may have encountered the problem that when you open the "My Computer--Explorer" in Vista or Windows 7 environment, Drive C shows a red bar (low disk space), while Drive F shows a blue bar, just as the following screenshot descriptive of the case:

C drive red bar

In the meanwhile, the system sometimes pop up a box "Low Disk Space", "You are running out of disk space on system(C:).  Click here to see if you can free space on this drive."

Low Disk Space

In fact, for most users, especially to some green hands, the situations above happened frequently, and it brought some results.

What will happen after low disk space on C drive?

Actually, when the red bar appears, the computer will run slowly for a long time. Besides, when you launch some application, it can’t be started or load successfully. Or when you want to close some application, but it won’t respond immediately or the screen becomes gray and unclickable.

What’s worse, you may find the time of boot time is becoming longer and longer, because the system partition stores too much or installs too many applications. The running space of the operating system is inadequate. Whatever the result is, all situations nearly drive users crazy.

Solutions to low disk space on C drive

How to correctly resolve this low disk space problem in Windows 10, 8, 7? After searching online resources and lots of experiments, I finally round up the following solutions and would like to share with you.

Solution 1: Run Disk Cleanup

You probably have saved some personal files to system partition. then you can drag them to another partition. Then run Disk Cleanup to delete some unwanted files. To open Disk Cleanup, you can right-click on C: drive and then select Properties>Disk Cleanup. Then Disk Cleanup will scan your C: drive and calculate how much space you can free, which may take a few munites. Within Disk Cleanup interface, select a few items and then click Ok to delete.

C drive cleanup

After that, you can click Clean up system files. From there, you can delete previous Windows installation (Windows.old folder), Windows update, temporary files, and other system files. In this way, it should free up much more space and solve the C drive showing the full issue.

Solution 2: Delete useless files from C drive

The second method is that you can use a Garbage Remover to scan useless files from Drive C and delete all of them for the purpose of releasing more free space to Drive C, such as the hiberfil.sys, pagefile.sys, temporary files of application programs (in Windows\temp menu) and temporary files created by Browser like IE, Firefox, and other browsers.  This method has one limitation that you can't resolve the problem thoroughly because your PC will quickly create more garbage to make the Drive C showing red bar again.

Solution 3: Extend C drive

The above methods can't resolve your low disk space problem as you expected. The most effective method to solve low disk space issue in Windows 10, 8, 7 is to extend the system partition to make it much bigger. For this task, the professional disk manager: AOMEI Partition Assistant Professional can satisfy you best. Its “Allocate Free Space” can directly transfer free space from one drive to another, such as from D drive to C drive. You can download the demo version for a free trial.

Step 1. Install and run AOMEI Partition Assistant Professional. Right click another partition with much free space and select “Allocate Free Space”.

Allocate Free Space

Step 2 . Here you can set how much space you would like to transfer to C drive and click “OK”.

From D to C

Step 3. Click “Apply” and “Proceed” to commit the pending operation.


Then the free space of D drive will be moved to C drive. Besides, its “Extend Partition Wizard” is aslo helpful for extending system drive without rebooting computer. Last but not least, this versatile partition manager also allows you to move applications from C drive to another drive so that you can release more space on C drive

App Mover


There are five editions in AOMEI Partition Assistant: Standard, Professional, Server, Unlimited, Tech. Different editions have different functions. You can choose anyone according to what situation you are in and what problem you want to solve. In this case, AOMEI Partition Assistant Professional Edition can solve your problem totally.