Command prompt window will be opened.
Step 2: Type diskpart and press Enter
Step 3: Type list volume and you'll see all partitions but NO Unallocated space.
Step 4: Type select volume 1 to give focus to the system C: drive.
Step 5: Type extend to proceed extending.
If you extend C drive again, you'll receive error message 'There is not enough usable free space on specified disk(s) to extend the volume.'
To better understand about this, I suggest open Disk Management (Press Windows and X on keyboard and select from the list).
From Windows 10 Disk Management, you'll see clearly the disk partition layout, and whether there is adjacent Unallocated space.
Better than Diskpart command line, Disk Management is graphical interface, so it is easier to most of computer users. The built-in Extend Volume function can help you enlarge partition on the fly.
However, the same with Diskpart, there must be adjacent Unallocated space on the right side of the partition that you want to expand, otherwise Extend Volume is grayed out.
Steps to enlarge partition with Windows 10 Extend Volume function:
Step 2: Extend Volume Wizard will be opened, simply click Next to continue.
Step 3: Select available disk and space, click Next to continue.
In a short time, volume D will be extended.
The only option to expand C drive is by deleting the adjacent volume (D:), however, it is not suggested, because:
Besides the limitations above, only NTFS can be extended, FAT32 and other types of partitions are not supported. The best way to extend partition in Windows 10 is running professional partition software such as NIUBI Partition Editor.
NIUBI Partition Editor provides basic partition management to create, delete, format partition, change drive letter, etc. Advanced management to resize/move existing partition without data loss, copy, hide, set active, convert, defrag, check partition and much more. It supports Windows 10, 8, 7, Vista and XP (both 32 and 64 bit). To resize and extend partition on Windows 10, you just need to click, drag and drop on the disk map.
The top reason: NIUBI Partition Editor has unique 1 Second Roll-Back technology to ensure system and data intact. Furthermore, it is 30% to 300% faster than other tools because of its advanced file-moving algorithm.
Steps to extend Windows 10 volume with NIUBI PE:
Download this software, you'll see the main window with disk partition information and available operations.
Step 1: Right click drive D and select "Resize/Move Volume", drag left border towards right in the pop-up window.
Step 2: Right click drive C and select "Resize/Move Volume" again, drag right border towards right in the pop-up window.
This software is designed to work in its virtual mode, remember to click Apply to confirm, otherwise real disk partition won't be changed.
If you have shrank drive D with Windows 10 Disk Management,
To extend drive C:
Right click drive D and select "Resize/Move Volume", drag the middle position rightwards in the pop-up window:
Unallocated space will be moved to behind C drive, then follow Step 2 above.
To extend drive E:
Right click drive E: and select "Resize/Move Volume" again, drag the left border leftwards in the pop-up window.
Then Unallocated space will be combined into E drive.
Watch the video how to resize and extend partition on Windows 10:
Windows built-in Diskpart command and Disk Management tool cannot extend a volume by shrinking other one or even by deleting the adjacent partition in some situations. To extend volume on Windows 10, third party partitioning software is much easier. Among these software, NIUBI Partition Editor has unique 1 Second Rollback, Cancel-at-well and Virtual Mode technologies to protect system and data. Besides resizing and moving partitions, it helps you do many other disk partition management.