how to add unallocated space to c drive

How to add Unallocated Space to C drive partition

By James, Updated on: March 16, 2021

This article introduces how to add Unallocated space to C drive without data loss, 3 ways to add Unallocated space to system partition on Windows Server & PC.

Applies to: Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, Windows Server 2019, Windows Server 2016, Windows Server 2012 (R2), Small Business Server 2011, Windows Server 2008 (R2) and Windows Server 2003 (R2).

Add Unallocated space

Unallocated space is part of disk space that is not belong to any partition. However, it doesn't mean it's blank. If there are files once saved to this area, they still can be recovered by some tools. To save new files to this area, you must create new volume with this Unallocated space and format with a file system.

Besides creating new partition, you can add Unallocated space to C: drive or other volume to increase free space. To add Unallocated space to a partition, Windows 7/8/10 native Disk Management is an option, but it can only add Unallocated space to the left contiguous partition. If you want to add to the right contiguous or any nonadjacent volume, you need 3rd-paty partition software. In this article, I'll introduce 3 ways to add Unallocated space to system C drive.

1. How to add Unallocated space to C drive partition after deleting D

To get Unallocated space you may either delete or shrink a volume. If you've gotten Unallocated space by deleting the contiguous partition D, follow the steps to add Unallocated space to C drive using Disk Management in Windows 10/8/7:

Press Windows and R together on the keyboard, input diskmgmt.msc and press Enter to open Windows Disk Management.
Right click C: drive and select Extend Volume.
Simply click Next till Finish in the pop-up Extend Volume Wizard.

This method is invalid for Windows Vista/XP and Server 2003, because there's no Extend Volume function in Disk Management.

If D: is Logical drive, its disk space will be converted to Free instead of Unallocated after deleting. In that case, Disk Management is unable to extend C drive. When you right click C drive, Extend Volume is grayed out. If you encountered this issue, you may use another native tool - diskpart command.

How to add Unallocated space to C drive using diskpart cmd (Windows 10/8/7/Vista/XP):

Press Windows and R keys together, input diskpart and press Enter.
Input list volume and press Enter in the command window, then you'll see all single partitions in a list. (Unlike Disk Management, Unallocated space is not listed).
Input select volume C and press Enter.
Input extend and press Enter, done.

If you don't like the command prompt tool, you may use free partition editor software.

2. How to add Unallocated space to C drive after shrinking D or E

If you got Unallocated space by shrinking D or other partition, You cannot add Unallocated space to C drive in Windows 10/8/7 Disk Management. Because the built-in Extend Volume function can only merge Unallocated space to the left contiguous partition. Unallocated space shrunk from D drive is nonadjacent to C, so Extend Volume is disabled. You have to move Unallocated space next to C drive in advance.

Steps to add Unallocated space to C drive after shrinking a volume:

Download NIUBI Partition Editor, right click D: drive and select "Resize/Move Volume", drag the middle towards right in the pop-up window. Then Unallocated space is moved from right side of D to the left.
Right click C: drive and select "Resize/Move Volume" again, drag right border towards right in the pop-up window, then Unallocated space is added into C drive.
Click Apply on top left to execute. (All operations before this step only works in virtual mode.)

Video guide

If the right contiguous partition is E: in your computer, simply replace D with E in the steps above.

3. Add Unallocated space to system C drive from another hard disk

In some computer, there's not enough free space on the same disk, but there's large amount on a separate disk, many people want to add Unallocated space to C drive from another disk.

In fact, neither Windows Disk Management nor 3rd-party software can do this. Because the size of a physical disk is fixed. A 500GB disk can't be decreased to 400GB or increased to 600GB.

In this situation, you need to copy system disk to another larger one, additional disk space will be shown as Unallocated at the end and it can be added to C drive easily.

Follow the steps in the video to add more space to C drive with another disk.

Video guide

In Summary

Windows native Disk Management and diskpart command can only add Unallocated space to the left contiguous partition, so it is useless in most cases. 3rd party software is better choice to accomplish this task, however, remember to back up first and run safe partition editor tool.

Better than other software, NIUBI Partition Editor has unique 1-Second Rollback, Cancel-at-well and Virtual Mode technologies to protect your system and data. In addition, it is much faster because of its special file-moving algorithm, saving much time while moving partition with large amount of files in it. Besides moving and adding Unallocated space to C drive or other partition, NIUBI helps do many other operations.

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