Most Effective Methods to Fix C Drive Out of Space Issue

by Jordan, Updated on: August 27, 2026

It is a headache for most Windows computer users when the system C: drive is running out of space. Microsoft does not provide a helpful solution other than running the Disk Cleanup utility to help free up disk space. Many people report that the C drive runs out of disk space again shortly after cleaning up the disk. This article introduces why the C drive runs out of space and how to fix the C drive out of space issue in Windows 11/10/8/7 and Server 2022/2019/2016/2012/2008. The steps are valid for all Windows versions. Of course, you may try all the methods found on Google, but few are effective. After following the steps below, you can fix C drive low disk space fast, easily, and completely.

Out of space

Why C Drive Is Running Out of Space in a Windows Computer

Whether you use a Windows laptop, desktop, or a server, you will encounter the annoying low disk space issue. Compared to a data volume, system partition C is very likely to run out of disk space. For a data volume, you can easily transfer files to another place, but for the system C drive, it is a bit complicated.

C drive out of space

There are many types of junk files generated or saved to the C drive continuously, for example, Temporary Setup Files, Downloaded Program Files, Temporary Internet Files, Recycle Bin, Cache, and Logs.

In both personal computers and Windows servers, you need to install many programs. The more you install, the less free space is left in the C drive. Many server administrators know the importance of changing the default installation path, but many files are still saved to the C drive.

Other large files such as system backups, restore points, and Windows Updates can eat up a large amount of free space easily.

When the system C drive is running out of space in Windows Server 2012/2008/2003 and Windows 7/Vista/XP, you will receive the Low Disk Space warning in the bottom right corner. In all Windows PCs and Servers, when the C drive is getting full, it will be marked in red in File Explorer. In this situation, you will begin to suffer from performance degradation. The less free space left in the C drive, the higher the risk of the computer getting stuck, rebooting unexpectedly, or even crashing. It is urgent, and this is the reason why Microsoft creates these warnings. Therefore, you had better try to fix the C drive out of space issue as fast as possible.

How to Fix C Drive Out of Space in a Windows Server/PC

When a data drive is getting full, you can simply transfer files to another place, but you cannot do this to the system C drive. As stated at the beginning, Microsoft only provides Disk Cleanup to help free up disk space. For most servers and PCs, this utility can reclaim disk space to some extent, but it cannot solve this problem completely. Even if you gain over 10GB of free space, it will be eaten up quickly. You should continue to add more free space to the C drive.

Step 1: Clean Up Disk to Reclaim Free Space

Cleaning up the disk cannot solve this problem completely, but it is still helpful. After gaining some free space, your laptop/desktop/server can keep running smoothly. In addition, there will be free space to install programs to help solve this problem.

To reclaim disk space, you may use either the Windows native Disk Cleanup tool or third-party software. The Windows Disk Cleanup tool is recommended because it is able to delete most junk and unnecessary files fast and safely.

Follow the steps to enable Disk Cleanup on Windows Server 2008 and 2012; other versions have it enabled by default.

How to fix C drive out of space issue with Disk Cleanup utility:

  1. Press Windows and R together on the keyboard.
  2. Type cleanmgr and press Enter.
    Cleanmgr
  3. Select C: drive in the drop-down list and click OK, then the Disk Cleanup dialog box will pop up.
  4. Click the check-boxes in front of the files that you want to remove, then click OK to confirm.

Disk Cleanup

If you want to reclaim more disk space, follow the steps to try additional methods in a specific OS:

Step 2: Add More Free Space to the C Drive

This step is indispensable, especially for computers where the C drive was created small. It is similar to a smartphone: if you use a 16GB device, you have to clean it up frequently. But if you use a 256GB device, you will not encounter this problem for a long time.

Disk partitions are already allocated, but you can resize a partition without losing data. It is very easy to add more free space to the C drive from other partitions. To do this, you just need to drag and drop on the disk map.

Download NIUBI Partition Editor and follow the steps in the video:

Video guide

This video was created on Windows 10; the steps are similar for other versions. Better than other tools, NIUBI has Virtual Mode, Cancel-at-will, 1-Second Rollback, and Hot-Clone technologies to protect your system and data. It has a free edition for Windows 11/10/8/7/Vista/XP home computer users.

Step 3: System Optimization

  1. Create a separate partition for programs and files; do not throw everything into the C drive.
  2. Change the program default installation path to another partition.
  3. For the programs you have installed on the C drive, change the default output path to other partitions. Programs for Games, Videos, and Projects output large files.
  4. If the entire hard disk is running out of free space, you may clone it to a larger one.
  5. Run Windows Disk Cleanup monthly to delete newly generated junk files.

In Summary

When the system C: drive runs out of space on Windows 11/10/8/7/Vista/XP or Windows Server 2022/2019/2016/2012/2008/2003, clean up the disk to get some free space, then add more free space to the C drive from other partitions, and finally, optimize your system settings. Finish the 3 steps above, and you will fix the C drive out of space issue completely.

➤