Add Unallocated Space to System C Drive

By James, Updated on: January 21, 2020

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).

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, you can add Unallocated space to C drive or other volume. Disk Management of Windows Server 2008 and subsequent versions can help you under some condition, but because of some inherent limitations, it is not the best tool. In most cases, you need to run disk partition software. This article introduces 3 ways with detailed steps to add Unallocated space to system C drive.

How to add Unallocated space to system C drive after deleting D

To get Unallocated space you may either delete or shrink a volume. If you got Unallocated space by deleting the contiguous partition D, follow the steps to add Unallocated space to C drive with Disk Management (without any software):

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

Do not delete drive D if you installed programs into it.

If drive D is Logical, its disk space will be converted to Free instead of Unallocated. In that case, Extend Volume is grayed out for C drive after deleting D.

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

If you got Unallocated space by shrinking D or other partition, Disk Management cannot add Unallocated space to C drive. Because Extend Volume can only merge Unallocated space to the left contiguous partition. Unallocated space shrank from D drive is nonadjacent to C, so Extend Volume is disabled.

Follow the steps to add Unallocated space to C drive after shrinking D:

  1. Download NIUBI Partition Editor, right click drive D 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.
  2. 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.
  3. 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.

Add Unallocated space to partition C from other hard disk

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

In fact, neither Windows Disk Management nor 3rd-party software can do this. In this situation, you need to copy system disk to another larger one, additional disk space will be shown as Unallocated and it can be added into C drive.

Video guide

In Summary

Windows native Disk Management can only add Unallocated space to the left contiguous partition, so it is useless if you cannot delete the right contiguous partition. 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 system and data. In addition, thanks to its special file-moving algorithm, it saves much time while moving D and other partitions. It is very helpful especially to a server. As a disk partition management toolkit, it helps do many other operations.

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