Unallocated space is kind of disk space that is not allocated to any partition. Beside creating new volume, it can be combined to other partition without losing data. To get Unallocated space, you may either delete or shrink a partition. Better than deleting a partition, you'll get Unallocated space by shrinking this partition without losing files in it.
After merging Unallocated space to C drive or another a partition, it will be changed to part of free space in this partition. Therefore, when system C: drive is running out of space, many people want to get Unallocated space and combine to C drive. If you use Windows 10 or previous Windows 8/7, the native Disk Management tool can help you in some cases.
Because of many serious defect, this native tool is not perfect, many people feedback that they can't merge Unallocated space. In this article, I'll explain the reason and show you how to merge Unallocated space in Windows 10/8/7 laptop/desktop without losing files.
Why Disk Management can't merge Unallocated space
Actually, there are 2 types of native tools in Windows 10/8/7 - Diskpart and Disk Management. Diskpart is a command line tool, Disk Management has graphic interface. Although they work in different way, they have same shortages while merging Unallocated space to a partition:
- They can only combine Unallocated space to NTFS partition, FAT32 any other types of partitions are not supported.
- They can only merge Unallocated space to the contiguous partition on the left.
- They cannot merge Unallocated space to a partition on another disk.
As I said in the beginning, it's better to get Unallocated space by shrinking a partition, because you won't lose files in it. Many people did shrink D drive, but after that they cannot merge Unallocated space to C drive or other partitions, why?
Because, Windows 10/8/7 Disk Management (and diskpart cmd) can only make Unallocated space on the right while shrinking D (and other partition), this Unallocated space is nonadjacent to C drive and on the left of E drive. As you see in the screenshot, Extend Volume is greyed out for both partitions.
If you want to merge Unallocated space to C drive using Windows 10/8/7 native Disk management tool, you must delete D: drive to get contiguous Unallocated space. If you want to merge Unallocated space to the right partition E, Disk Management (and diskpart) cannot help you.
Note: do not delete D if you installed programs in it. If D is a Logical drive, you still cannot extend C drive after deleting it.
Another probable reason why you cannot merge Unallocated space to a partition in Windows 10/8/7 is related to MBR disk limitation. On a MBR disk, you can only create maximum 2TB partition, if you want to combine more Unallocated space to it, you must convert MBR disk to GPT in advance.
How to merge Unallocated space in Windows 10/8/7
To combine Unallocated space to a volume in Windows 10/8/7 computer, you'd better run third party software. There are many choices, among them all, NIUBI Partition Editor is much better, because it has unique 1-Second Rollback, Virtual Mode and Cancel-at-well technologies to protect your system and data. It has free edition for Windows 10/8/7/Vista/XP home computer users. To move and combine Unallocated space, you just need to drag and drop on the disk map.
Download the free edition and you'll see the main window with disk partition structure and other information.
1. How to merge Unallocated space to C drive (nonadjacent)
As I explained above, after shrinking D drive in Disk Management, Unallocated space is on the right of D. In this situation, you can move Unallocated space to the left with NIUBI Partition Editor, and then combine to C drive.
Steps to merge Unallocated space to C drive in Windows 10/8/7 with NIUBI:
- Right click D: drive and select "Resize/Move Volume", drag the middle towards right in the pop-up window, then Unallocated space is moved to the left side.
- Right click C: drive and select "Resize/Move Volume" again, drag right border towards right to merge this Unallocated space to C: drive.
- Click Apply on top left to confirm and execute. (To avoid mistake, all operations you do will be listed as pending, real disk partitions won't be modified until click Apply to confirm.)
Follow the steps in the video:
If you use any types of hardware RAID arrays, or run Windows 10 as guest virtual machine in VMware or Hyper-V, simply follow the steps in the video, there's no difference. In some computers, the contiguous drive is E. In that case, replace D with E in above steps.
2. How to merge Unallocated space to a contiguous partition
To merge Unallocated space in Windows 10/8/7 to a contiguous partition, it is very easy with NIUBI Partition Editor, there's only one step, following the methods below.
① Merge Unallocated space to the left contiguous partition:
Right click D: drive and select Resize/Move Volume, drag right border towards right in the pop-up window.
Then Unallocated space is merged into D drive.
If you want to add Unallocated space to a 2TB partition, follow the step to convert MBR disk to GPT and then follow the method above.
3. Merge Unallocated space to another disk
In some computers, there's no data volume on the system disk, or there's not enough free space on the same disk. Some people are wondering whether it's possible to add Unallocated space to C drive (or other volume) from a different/separate disk. The answer is no.
To physical hard disk drives, there are two options:
- Move a partition to another disk, delete it to get Unallocated space and then add to C drive.
- Copy whole disk to a larger one and extend partition with additional disk space.
If you use virtual machine, it is much easier, you can expand original virtual disk following the steps in VMware or Hyper-V. After expanding disk, additional space is also shown as Unallocated at the end of disk, then follow the steps above to merge Unallocated space to C drive or other partition.
Besides moving and merging Unallocated space in Windows 10/8/7/Vista/XP, NIUBI Partition Editor helps do many other operations such as copy, convert, defrag, wipe, hide partition, scan bad sectors, etc.