By Dylan / Last Updated February 12, 2020

What does unallocated space mean?

Unallocated space is the space that is not allocated to any partition in your disk yet, so it does not belong to any partition, and you can’t write data, file, and programs to the space. In most cases, there are two conditions will generate some unallocated space in your disk.

  • Deleting or shrinking a partition. When you delete or shrink a partition, the space that was shrank or deleted will turn into unallocated space.

  • A hard drive shows less than its capacity. It is a common case, MBR partition format only supports the maximum capacity of 2TB, if the MBR hard drive space is beyond the limit, the rest of space will become unallocated, like a 4TB hard drive only shows 2TB. Thus, you need to convert the MBR disk to GPT, which supports a hard drive with much larger space.

Generally, we suggest you use unallocated space in Windows 10 for creating a new partition or merging it into C partition, or other partition. In this way, you can manage more files constantly generated on your disk so as to avoid your disk space being insufficient. And next, we will guide you how to use unallocated space in Windows 10.

How to use unallocated space in Windows 10?

To allocate unallocated space, you might think about using the Windows 10 built-in tool Disk Management. It can indeed help you to create a new partition and merge the unallocated space to another space. You can press “Win + R” to launch Run box, and type “diskmgmt.msc” to open Disk Management. And right-click on the unallocated space to create a partition or add it to another partition.

But we don’t recommend this way because the Disk Management has a limitation to extend a partition: it can only extend a partition with a contiguous unallocated space, otherwise the “Extend Partition” option will be greyed out. And it doesn’t allow you to move any partition.

You can turn to another more powerful and flexible Windows disk manager-AOMEI Partition Assistant Standard. It can directly merge unallocated space to another volumes or partition, and create a new partition on unallocated space or directly from other partitions. And its intuitive interface makes all the steps easy-to-operate. You can refer to the following steps to see how to use this tool.

Note: Sometimes, you may fail to create a partition on unallocated space. It may be because your disk uses MBR partition table which can only have at most 4 primary partitions and 1 extended partition. You can use AOMEI Partition Assistant Professional edition to convert MBR to GPT disk that supports 128 primary partitions before creating.

Use unallocated space to create a new partition

Step 1. Download and Launch AOMEI Partition Assistant, right-click on the unallocated space, and choose “Create Partition”.

Create New Partition With Unallocated Space

Step 2. In the small window, you can decide the size of the new partition by dragging the bar.And click “OK”.

Specify Partition Size

Note: You can click “Advanced” to create logical or primary partition, and set file system and partition label.

Step 3. Then click “Apply” in the main interface to start creating partition.

Click Apply

Merge unallocated space to another partition

Step 1.In the AOMEI Partition Assistant main interface, right-click on the partition you want to merge, here we choose the C partition, and select “Merge partitions”.


Step 2. Choose the unallocated space, and click “OK”.


Step 3. Likewise, click “Apply” in the main interface to start the merging operation.



Speaking about how to use unallocated space in Windows 10, I believe the best answer is to create a new partition, or add the unallocated space to another partition via AOMEI Partition Assistant. In addition, this specialist software provides more features, like copy partition, wipe partition, to make your computer’s partition management more convenient than before.

You can also upgrade to Professional edition, which offers lots of advanced features: extend partition, convert file system between FAT32 and NTFS without data loss, migrate OS from MBR disk to GPT disk. And if you want to merge 2 partitions that are not adjacent, you can use it to move the partition to make them contiguous.