Best Way to Increase C Drive Space in Windows 7/8/10

Increasing C drive (normally system partition) space without formatting hard drive or reinstalling OS in Windows 10/8/7 is a common problem. AOMEI Partition Assistant provides excellent schemes to extend C partition without data loss in Windows 7/8/10.


By Lucas / Updated on May 12, 2023

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The necessary to extend C drive (system partition)

You may have encountered this issue once: applications are installed in C partition constantly, one day you’ll find the C partition lack of enough space; or there would be a warning to remind you that the C partition runs out of space when start your PC every time. At the same time, there would have a direct impact on the efficiency of computer operation. You have to make more space for C drive.

Then, you will find some ways to solve the problems, delete the unnecessary files and uninstall programs, or clean up your recycle bin; then you can get some spare room in the C drive. But, after a time, the same problems will come to bother you again. Thus, you must look for other reliable methods to solve it. The solution to the problems above mentioned is to increase C drive space.

How to increase C drive without formatting in Windows 7/8/10?

There are three solutions to achieve this function without data loss: Windows built-in Disk Management, Command Prompt (CMD) and AOMEI Partition Assistant. How to extend C partition in Windows10/8/7? Just follow the following text:

Solution 1: Windows system built-in Disk Management

The built in Disk Management have many functions to manage your disk, including extend volume, shrink volume, format partition, etc. By extending disk, increase C partition as you want.

Disk Management Extend Volume

But the extend volume function has a weakness, no unallocated space behind the C drive will makes the "Extend Volume" grayed out. Besides, move partition isn’t supported by Disk Management. Thus, you need to seek for other options.

Solution 2: Extend system partition (C: drive) using CMD

You have to be careful to run these commands to make sure you can move more space to C: drive successfully. Here are the tips:

If there is a contiguous unallocated space behind the system C: drive, you can follow below steps:

1. Input diskpart in the Search Bar, and hit enter.

2. then input these commands in turn:

  • list disk

  • select disk n (the n is the disk letter of your system hard disk)

  • list partition

  • select partition n (the n is the volume letter of the system C drive)

  • extend

  • exit

If here is no unallocated space right behind the system C: drive, follow below steps:

1. Input diskpart in the Search Bar, and hit enter.

2. then input these commands in turn:

  • list disk

  • select disk n

  • list partition

  • select partition n (the n is the volume letter of the partition behind C drive)

  • delete partition

  • select partition m( the m is the volume letter of the C: drive)

  • extend

  • exit

If this way is not working for you, another reliable way should be suitable for increase C drive space in Windows 7/8/10.

Solution 3: The third party freeware - AOMEI Partition Assistant Standard

AOMEI Partition Assistant provides more functions than Disk Management, including resize partition, move partition, merge partitions, split partition, create partition, copy partition, delete partition, change label, wipe partition, hide partition and check partition etc. It also provides several ways to increase system partition in Windows 7/8/10/11 with extend partition wizard and merge partitions function. The following steps are according to merge partitions.

Download FreewareWin 11/10/8.1/8/7/XP
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Step 1: Download and launch the AOMEI Partition Assistant Standard Edition after installing. If there is an unallocated space on the same hard disk, please skip to the Step 3. Otherwise, use the Resize Partition to generate one (Free an unallocated space from D partition). Right click the D partition and select Resize/Move Partition. (This function also supports resizing BitLocker partition.) 

Resize Partition

Step 2: Shrink D partition to get an unallocated space by sliding the double sided arrow to the left. Then, click OK.

Drag to Left to Shrink

Step 3: Right-click the C drive and select AdvancedMerge Partitions.

Merge Partitions

Step 4: Tick C partition and the unallocated space to merge in the pop-up window, and then click OK.

Merge C and Unallocated Space

Step 5: Click Apply to combine C drive and the unallocated space in Windows 7/8/10.

Apply Merge C and Unalloated Space

Step 6: Click the Proceed button to start. Wait a minute to finish this and you’ll find the C drive space increased. 


  • If applications running in the partition, AOMEI Partition Assistant will suggest you to close or perform extend partition operations under PreOS Mode.

  • If there is an unused partition on the disk; you can also use the Delete Partition to get an unallocated space. AOMEI Partition Assistant also provides other features, including move partition, copy partition and more.

  • The Extend/Shrink Partition function is realized by the Resize Partition feature that depend on whether there is an unallocated space or not.

After these excellent ways to increase C drive space, your C drive will get enough free space to hold more data and running quickly. Besides, you could upgrade to the Professional edition with more advanced functions to manage your hard disk, like allocate free space from one partition to system partition, migrate OS to SSD, and others. Or you could try the Server edition for your Windows Server computers.

Lucas · Staff Editor
I prefer peaceful and quiet life during vacation,but sometimes I watch football match if my favorite club performs brilliantly in that season. And I love reading, painting and calligraphy, thus I send my friends festival handwriting cards every year.