By Lily / Last update October 21, 2022

The issue: cloned hard drive unallocated space left

Recently, disk clone has become more and more popular among computer users. It refers to the process of copying all the data from one hard drive to another, including the operating system, applications and user files, etc. What’s more, the cloned drive will keep the same partition style and file system as the original drive, so you can just use it as a replacement of the source drive. You may need to clone a disk in following situations:

  • Upgrade a smaller drive to a larger drive when the current drive is running out of space.

  • Upgrade an HDD to an SSD to enjoy the benefits of SSDs such as faster speed, less noise, and less power consumption.

  • Get a spare disk which contains all the data you have on the current system disk, so you can use it in emergency.

However, some users find the cloned drive contains unallocated space after they clone a smaller drive to a larger drive. The unallocated space can’t be used to store data, which makes cloning to a larger disk no sense. The storage space isn’t enlarged at all! Here is a real case:

“Hi everyone,

I cloned my 256GB hard drive on a new 1TB hard drive. The cloning and physical install went smoothly but now I have almost 700 gigabytes on unallocated space. My C: drive is showing as if it is still near capacity so I need to figure out how to utilize my new disk space. Can I add this unallocated portion to my C: drive?” 

How to deal with unallocated space after cloning via Disk Management

To deal with unallocated space after cloning a hard drive, you may take advantage of a Windows built-in tool—Disk Management. In my case, I have cloned disk 0 (931.30GB) to disk 1 (1023.98GB) and there is 92.68GB unallocated space left.

Unallocated Space Left

Learn detailed steps to extend the cloned partition with unallocated space below:

1. Right click on This PC and hit the Manage option. In the pop-up window, click Disk Management on the left panel.

2. Right click on the partition you want to extend and select Extend Volume. Then, follow the Extend Volume Wizard to complete the process.

Extend Volume

3. (Optional) You may be prompted to convert the selected basic disk to dynamic disk if you extend the partition into non-contiguous unallocated space. If you are not sure, learn more from “Should I convert to dynamic disk?”.

Convert to Dynamic

Tip: For logical drives and boot or system volumes, you can extend the volume only into contiguous space and only if the disk can be upgraded to a dynamic disk. For other volumes, you can extend the volume into non-contiguous space, but you will be prompted to convert the disk to dynamic.

Powerful disk cloning software to clone disks without unallocated space left

To solve the issue “cloned hard drive unallocated space left”, you can also use a kind of disk cloning software that is able to deal with unallocated space during the cloning process. AOMEI Backupper Professional is such a tool you can rely on.

  • With the inbuilt clone feature, you are allowed to clone only the operating system, an entire disk, or specific partitions.
  • If you are cloning hard drives with different sizes, you may edit partition size on the destination disk during the cloning process.
  • If the two disks are in same size, you may use sector by sector clone to conduct 1:1 copy.

Learn how to use AOMEI Backupper to clone to a larger drive without unallocated space left as follows:

Step 1. Connect the target drive to your computer and make sure it is detected. Backup files on the target drive if necessary, because all data in the destination will be deleted in the cloning process.

Step 2. Install and launch AOMEI Backupper. Click “Clone” on the left pane and select “Disk Clone”.

Choose Disk Clone

Step 3. Select the current hard drive as the source disk and click “Next”.

Choose Source Disk

Step 4. Select the larger drive you have connected to your PC as the destination disk and click “Next”.

Choose Destination Disk

Step 5. In the Operation Summary page, click on “Edit partitions” and then choose from the two options below:

Add unused space to all partitions: the program will automatically add unallocated space to all existing partitions.

Add Unused to All

Manually adjust partition size: you can click on each partition and resize it by dragging the side bar.

Manually Adjust

Convert the destination disk from MBR to GPT: It helps to convert the partition style of the destination disk if it is different from the source disk, for example, clone GPT disk to MBR or vice versa. Then, how to distinguish the disk type (MBR or GPT)? You can dheck it in the Disk Management.

  • Press Win + R to open the Run window. Then, type diskmgmt.msc and hit OK to open disk management.
  • Then, right-click the disk you want to clone and select Properties in the pop-up window.
  • In the Properties window, select the Volume tab and confirm the partition style. It can be MBR (Master Boot Record) or GPT (GUID Partition Table).

Disk Partition Style

Step 6. Click on “Start Clone” to execute the operation.

Start Clone


  • To boot from the cloned drive after cloning, you may change boot order in BIOS or just replace the original drive with the target drive. If the two drives are in different partition types (one MBR, one GPT), you may change boot mode in BIOS to boot from the cloned drive.

  • If you are cloning disk to an SSD, you can tick the option “SSD Alignment” before you click “Start Clone”, thus improving the reading and writing speed on the destination SSD.


Now you know how to fix the issue “cloned hard drive unallocated space left”. You can either use Disk Management to extend volumes with unallocated space or use advanced disk cloning software to clone hard drives. With AOMEI Backupper, you won’t need to worry about unallocated space after cloning. You can handle it easily during the cloning process.

In addition, AOMEI Backupper can be used as backup & restore software. It enables you to backup multiple drives in Windows 10 and restore Windows backup to another computer. Try it now to discover more!