How to Increase C Drive Space in Windows 11/10/8/7?

Position: How Tos - Partition Management - How to Extend C Drive Space in Windows 11/10/8/7?

Are you running out of space in C drive (system partition) where operating system is located? Do you know how to increase C drive space without losing data? In this article, we can find several solutions to safely increase system partition size without formatting or reinstalling OS in Windows 11/10/8/7.

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Table of Contents:

About increasing C drive space

How do I increase C drive space without losing data in Windows 11/10/8/7? This is one of the most frequently asked questions when you browse technical forums or communities. Computer will slow down and reduce performance if C drive where operating system is installed is running out of free space. Here is one of the posts found on related forums.

"Hello everyone, I would like to ask whether it is possible to increase space for C drive without formatting my laptop or losing any data. I bought this laptop with 4 partitions, system (C:), document (D:), photos (E) and local (F:) and they are built in volume by default. The C drive has 85GB space and there other with 200, 350 and 350 in order. The C drive is almost full of data and I cannot install any other applications. I've deleted everything that I can from C drive. It is way too complicate to reparation the disk and reinstall Windows. I want to resize Windows partition so as to increate system partition size without disturbing existing data. Thanks."

Low disk space is one of the issues that many users may encounter. With the passage of time, Windows C drive is not large enough to install application and it is running out of space. You receive error message from system:

"Low disk space. You are running out of disk space on system (C:). To free space on this drive by deleting old or unnecessary file, click here…"

"Low Disk Space. You are running out of disk space on Local Disk (C:). Click here to see if you can free space on this drive."

In many causes, the partition layout on hard drive seems reasonable when computer was originally set up. It is for sure that a majority of users allocates disk space based on specific requirement, and all of them have tried best to make sure system partition is well configured in order to achieve best performance. However, unfortunately, C drive still runs out of space much earlier than other volumes. You might have installed too many applications and stored large amount of data on C drive. Anyway, system partition does not have much free space now, and computer slows down a lot. It is difficult to for most users to reinstall Windows again, as the process is kind of complicated and time-consuming. Thus, the ideal solution is increasing C drive space without affecting existing data.

How to increase C drive free space in Windows 11/10/8/7?

There are several ways you can try to increase free space in Windows 11/10/9/7, and you have a try.

  • Free up disk space in C drive: You can delete unnecessary files from C drive and uninstall non-frequently used programs. Thus method cannot free up enough space, and you will face low disk space issue soon.
  • Run the Disk Cleanup utility: Disk Cleanup removes temporary files, clears the cache, empties your Recycle Bin, and removes a variety of other files and items you no longer need.
  • Extend C drive: You can increase C drive space by extending C drive : add free disk space to system partition or move free space of other partition to C drive. Resizing partition in Windows is common operation and it does not cause data loss.
  • Repartition hard drive: hard drive repartitioning can reallocate disk space, and you can arrange large space for system drive. However, the process removes all partitions on the disk, and you need to backup data in advance.

Method #1: Increase C drive space in Disk Management

Windows Disk Management provides extend volume feature which is able to increase partition size by adding unallocated disk space and the process does not cause data loss. But not all partition can be extended in Disk Management, for instance, unallocated space can only be added to adjacent partition.

Step 1. Right-click on Windows Start button and select Disk Management. This will launch Disk Management console.

Step 2. Right-click on C drive in Disk Management and choose Extend Volume option. Then the Extend Volume Wizard shows up.

Step 3. Click Next button on the Extend Volume Wizard welcome interface.

How to Increase C Drive Space

Step 4. Set disk space to be added to C drive and click Next button.

Note: the volume size you enter here is in megabytes (MB) and you can follow the default setting if you do not have other requirements.

How to Increase C Drive Space

Step 5. Click Finish button when the process completes and you'll return to Disk Management and the C drive will be extended successfully.

Limitation on Disk Management to increase C drive space:

  • Extend Volume option is available for NTFS partition, and FAT32 partition and exFAT partition are not supported.
  • There should be unallocated disk space next to the partition you want to expand and the unallocated space is on the right side in order.

Thus, if there is not free disk space next to C drive (usually on the right-side), the Extend Volume option will be grayed out. In that case, you can delete the adjacent partition to get unallocated space and then add it to C drive, or you can move disk space from other partition to C drive using third-party software.

Method #2: Extend C drive with free disk partition software

If you find the Extend Volume option is grayed out in Windows Disk Management, you will need to delete D drive which is the partition on the right side of C drive, so that you can create unallocated space and add it to C drive. You need to transfer data of D drive to other partition or external hard drive before deleting it. However, there is an ideal alternative solution to increase C drive space without deleting any partition.

DiskGenius Free provides the function to extend partition and it is able to move free disk space from other partition to C drive directly. Apart from extending partition, it is able to resize volume, create partition, wipe partition, hide partition, clone & image partition, check bad sectors, recover lost data, etc. The follow steps shows how to extend C drive in Windows 10.

Step 1. Download and launch DiskGenius Free Edition after installing on your computer. Right-click on the C drive you want to increase space and choose Extend Partition.

How to Increase C Drive Space

Step 2. The Extend Partition window shows up, and you need to choose a partition which contains large free space and click OK button.

Partition selected in this step should contain enough free space, as the software will move free space from this partition to C drive.

How to Increase C Drive Space

Step 3. Set the disk space to be moved to C drive and click Start button. You can drag the partition bar to set partition size or type in the exact size in the column.

How to Increase C Drive Space

DiskGenius lists steps to be done during the resizing process and things you need to note. Click Yes button to continue.

How to Increase C Drive Space

Changing partition size involves too many operations, such as modify partition start and end location, change parameters in MBR and DBR, move data, etc. therefore, the process is not risk free even if the partition manager software is stable. This it is advised to ensure follow matters to guarantee the process completes successfully:

  • There are not bad sectors on the disk, especially related partitions.
  • Make sure power supply works well and do not shut down computer before the partition resizing finishes.
  • Close all other programs that accessing the partitions to be moved space.
  • Disable system hibernate so that computer won't go hibernate during extending C drive.

Due to the partition to be extended is system volume, DiskGenius will boot to its WinPE edition to complete rest operations. Now it is preparing for the WinPE environment for DiskGenius WinPE edition, after which computer will reboot to the WinPE edition automatically.

How to Increase C Drive Space

Now DiskGenius WinPE edition is launched automatically and continues to extend C drive, as below. When the resizing process completes, computer will restart to Windows automatically.

How to Increase C Drive Space

Method #3: Increate system partition size using diskpart commands

Diskpart is Windows built-in utility, and it includes functions to manage disks and partitions via commands. Here are steps to increate C drive space via diskpart command:

Step 1. Right-click Windows 10 Start button and select Windows PowerShell (Admin) option.

Step 2. Type diskpart in Windows PowerShell and press Enter key.

Step 3. Type follow commands in turn and press Enter key after each command.

List volume

Select volume # (Replace # with the volume number of C drive)

Extend size=xxxx (replace XXXX with disk size in MB you want to add to C drive)

How to Increase C Drive Space

Limitations on diskpart when increasing partition size:

  • The partition to be extended should be in NTFS file system.
  • There should be contiguous unallocated space on the right side of partition to be extended.
  • Users who are not familiar with using command prone to making mistakes and leading to data loss.

Method #4: Increase C drive space by adding unallocated space

What to do if there is unallocated disk space which is not adjacent to system partition? Do you know how to add unallocated space to C drive so as to increase C drive space without losing data? Here is any easy solution:

Step 1. Launch DiskGenius from your computer and locate the free disk space from system disk.

Step 2. Right-click on the free disk space and select Allocate Free Space To , as follows. Then you can select a target partition to add the unallocated space. In this example, we want to increate system partition size, thus we need to select C drive.

How to Increase C Drive Space

Step 3. Partition resizing wizard will pop up and you can follow prompts to complete following actions.

Conclusion on resizing Windows partition

In conclusion, this tutorial presents four solutions to increase C drive space without formatting computer or losing any data in Windows 11, Windows 10, Windows 8, Windows 7, Windows Vista and Windows XP. Disk Management works in very few situations, and you can use third-party disk partition software in most cases to extend C drive. DiskGenius Free is free tool to manage disks and partitions and helps make best of disk space. If you have any questions or need any help in using DiskGenius, please feel to contact our technical support team.


1. Why does my C drive is running out of free space?

The reason for insufficient space on the C drive:

  • There are too many junk files and temporary files in the C drive.
  • There are too many programs that are not commonly used.
  • The partition capacity of disk C is too small.

2. How to obtain larger C drives and faster computers?

Backup Big data to external storage device: If you have saved a certain number of large files on your C drive but do not need to use them frequently, we recommend that you back up these files to an external storage device. You can apply DiskGenius or Isoo Backup to get help.

Regularly delete useless large files from drive C: Deleting old or unnecessary files on the system drive will free up space to ensure the normal operation of the Windows system.


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