By Michael / Last Updated June 25, 2021

Scenario: I’m upgrading my 120GB PNY SSD to a 500GB Samsung 850 SSD but here comes the question. I cloned the 120GB one using EaseUs Todo Backup onto the larger one. The cloning process was successful. However, I found that I had 354Gb that was unallocated on my larger SSD. Why and is it possible to extend partition with the unallocated space after cloning?

Why Do You Want to Extend Partition After Disk Clone?

People usually clone their disk from one to another for following for different reasons. For instance, they need to replace their old HDD with a new SSD for quicker loading speed in games and better performance. Besides, when their old hard drive is nearly full and they need to transfer all data to a new one, cloning a disk is an easier way. Thirdly, some users hope to save important data on an individual disk which is safer.

However, people who finish disk clone may find that the cloned disk is much smaller than before. Why does this issue keep happening? In fact, it’s very easy to understand - If you clone data from a smaller disk to a larger one, usually, you clone data byte by byte. You get the same layout for you clone exactly the same file system and partition tables. You get a same copy on the cloned disk while the extra space will be set as unallocated. To make the fullest use of entire disk space, you might need to extend partition with the unallocated space after disk clone.


2 Ways to Extend Partition after Cloning

You don’t have many options when it comes to enlarge partition after cloning. However, indeed, there are 2 methods you can try for free when this has to be done. One is Disk Management provided by Windows and the other is AOMEI Partition Assistant Standard. Both of them are easy and safe ways to extend partition but the product of AOMEI is more feature-rich. Beside extending partition, it can also help you do things like migrating OS from MBR to MBR and cloning partitions. So, which one to choose relies on your own needs.

Solution 1. Extend Volume with Windows Disk Management

1. Right click on “Computer” and select “Manage”.

2. Click on “Disk Management” under “Storage” on the left of the window.

3. Now, in the new window, you can see all disks and all partitions. Find the partition next to the unallocated space and right click on it.

4. Select “Extend Volume” and click on “Next > “Next” > “Finish”.

Extend After Delete

5. Now, you’ve successfully put the unallocated space to an existing partition.     

Solution 2. Enlarge Partition with A Third-Party Free Tool

I must admit that Windows’ inbuilt Disk Management is popular and many people use it. However, the option of “Extend Volume” will be greyed out when the unallocated space and the to-be-extended partition is not adjacent or the partition you want to enlarge is not NTFS. 

Extend Volume Grey Out

In these cases, I recommend to try AOMEI Partition Assistant Standard, with which you can extend both NTFS and FAT32 partitions. Besides, its “Merge Partitions” allows you to directly merge non-adjacent unallocated space into another partition easily. Or you can use “Move Partition” to move the middle partition between the unallocated space and the partition you wish to extend to the left, and make unallocated space and target partition adjacent. By contrast, the “Merge Partitions” save several steps and much time. So amazing, isn’t it?

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Step 1. Launch the program. Then, on the interface, you can see all your disks and partitions.

Step 2. Right click on the partition you hope to extend and select “Merge Partitions”.

   Merge Partitions After Clone

Step 3. Select the partition you want to merge and hit “OK”.

Tick All Unallocated Space

Step 4. Click on “Apply" on the upper left and hit “Proceed” to start the merging process.

Apply Merge Partitions After Clone

How to Avoid “Unallocated Space” Issue after Cloning?

People use software like EaseUs frequently encounter the issue of “unallocated space” after cloning their disk to another. Is there any way to avoid this upsetting thing so that we can save more time? Luckily, AOMEI Partition Assistant Standard is able to fit the source disk’s partitions to the entire destination disk so that there will be no unallocated space left.

1. Spot the source disk and the target disk on the interface.

2. Select the source disk, right click on it, and select “Clone Disk”.

3. Select “Clone Disk Quickly” and click on “Next”.

Copy Disk Quickly

4. Choose a target disk to clone the source disk to and still, click on “Next”.

5. Select the option of “Fit partitions to entire disk” and click on “Next” > “Finish”.


6. Click on “Apply” on the top left of the window to begin the clone process. In several seconds, you’ll find your entire old disk is copied to the other one with no unallocated space created.



Windows’ Disk Management and AOMEI Partition Assistant Standard - which one is better when you need to extend partition after cloning? The first one is an inbuilt tool which doesn’t need to be installed again but sometimes the option “Extend Volume” is greyed out. The latter one is also free and can not only help you extend partitions but also avoid unallocated space in the course of clone. And for more features including extending partition wizard and wipe system disk, you should upgrade this software to professional edition. Now, I believe you already have an answer in mind.