Fixed: Cannot Extend Volume to Unallocated Space in Disk Management

Help! Cannot extend the C drive

When trying to add space to the C drive or other partitions on Windows 11 or 10, you may encounter the error that the Extended Volume is grayed out. Don't worry, on this page, we will discuss why the Extended Volume option is grayed out and how to fix it on Windows 11, 10, 8, 7 and even Windows Server.

Disk management can't extend volume to unallocated space

When partitions are not divided properly, you may encounter a problem that some partitions are running out of space, as time goes by. This will influence the computer performance. Especially when C drive is full of applications and data, the running speed of your machine will reduce significantly. Then, you will need to extend the small volume or even to upgrade to larger disk if the capacity of your existing hard disk is too small.  

If other partitions have enough space on the hard drive, you can move programs from C drive to the partition that has enough space. 

If there is unallocated space available on the hard drive, you can extend the volume by adding into the allocated space using the "Extend Volume" feature of Windows 11, 10, 8, 7 built-in Disk Management tool. Just open the Disk Management, right-click the partition which you want to extend, and then select the "Extend Volume" in the drop-menu. Unfortunately, you may find that the Extend Volume grayed out, and you can't extend volume to unallocated space as expected.

Why Windows cannot extend volume to unallocated space?

Windows cannot always extend a volume to unallocated space for a few reasons. Here are some of the most common ones:

✦ Scenario 1: Unallocated space is not always next to the volume you want to extend

When you create a new partition or delete a partition on a hard drive, the resulting unallocated space might not be adjacent to the volume you want to extend. In this case, Windows cannot extend the volume to the unallocated space.

It means the “Extend Volume” function only works when the unallocated space is in the adjacent right side of the to-be-extended volume. Otherwise, the “Extend Volume” will be disabled.

✦ Scenario 2: Logical drive contains extended partition

Although there is unallocated space on the right side and adjacent to the target drive, the Extend Volume option is still gray. Why? That's because the partition is logical drives contained in an extended partition, which cannot be extended. As a workaround, you have to delete the logical partition first, then delete the extended partition, so that you can create logical partitions again.

✦ Scenario 3: Wrong file system formatted

Disk Management cannot extend volume to unallocated space if the target primary volume is formatted with FAT32. The Extend Volume only supports NTFS and RAW partition.

✦ Scenario 4: Outdated Windows system

The Extend Volume function built-in Disk Management tool since Windows 7. Before Windows Vista, there is no function to extend volume in Disk Management.

✦ Scenario 5: Partition style doesn't support large disk space

The partition style is incompatible. If the partition style of the hard drive is Master Boot Record (MBR), you cannot extend a partition beyond 2 terabytes (TB) of space. If you want to extend a partition beyond 2TB, you need to convert the partition style to GUID Partition Table (GPT).

In summary, Windows cannot always extend a volume to unallocated space due to various technical limitations, such as the partition style, file system compatibility, and the physical arrangement of partitions on the hard drive.

Easily extend volume to unallocated space with partition software

When Disk Management cannot extend volume on Windows 10, Windows 8, Windows 7, as well as Windows 11, you can switch to a partition manager named AOMEI Partition Assistant. You can use it to extend either NTFS or FAT32 volume in all versions of Windows 11/10/8/7 (32-bit and 64-bit). It also has Server Edition specifically for Windows Server OS, including Windows Server 2022, 2019, 2016(R2), 2012(R2).

Much better and more powerful than Windows Disk Management, it is able to move partition to make unallocated space contiguous to the volume you wish to extend, so that you can extend it using the "Extend Volume" feature.

Besides, it comes with the “Merge Partitions” function, allowing you to merge adjacent or non-adjacent unallocated space into the target volume within 3 steps. The latter is much easier and time-saving. You can download the software to see how to solve the Windows cannot extend volume issue.

Step 1. Install and run AOMEI Partition Assistant. Right-click the partition you want to extend, right-click "Advanced" and select "Merge Partitions".

Step 2. Then, tick the box before the unallocated space.

Step 3. After that, click "Apply" to execute it.

Option 1. Resize partition

Besides, its “Resize Partition” feature can extend volume to the adjacent unallocated space no matter it is on the right side or left side. Just right-click the target volume, select “Resize Partition”, drag the edge towards the blank space to extend the volume. After that, click Apply to submit the operations.

Option 2. Allocate free space

In addition, if there is no unallocated space, you can try “Allocate Free Space” feature, which has more advanced features waiting for you to unlock.  Allocate Free Space allows direct transfer of space from one volume to another (like from D to C) without damaging the data.

Step 1. Right-click the D drive and choose "Allocate Free Space".

Step 2. In the new window, you can specify the space size and target partition. If it’s C drive, you need to select C drive from the given list, and click “OK”.

Step 3. Now, you can preview that the C drive has been extended. Then, click Apply to save the changes.

Summary

See? AOMEI Partition Assistant software provides more than one sure-fire solutions to "cannot extend volume to unallocated space in Disk Management" problem. Additionally, you can also use the Extend Partition Wizard to extend the non-system and system partition without rebooting the computer. What’s more, it is featured with many other useful functions like making conversion between NTFS and FAT32 without formatting, converting GPT to MBR or MBR to GPT without deleting partitions, wiping hard drive and so on.