By AOMEI / Last Updated July 17, 2019

Why can’t you create partition from unallocated space?

“Unallocated space cannot create partition in Disk Management”, “I cannot create new partition from unallocated space in Windows 8”... such kinds of problems appear commonly in a lot of forums. Why will this happen exactly? Well, it might have something to do with the formats of hard disk - MBR andGPT.

MBR (Master Bootable Record) supports the maximum capacity with 2TB only, up to four primary partitions or three primary partitions plus one extended partition. While GPT (GUID partition table) supports more than 2TB, almost unlimited number of partitions. So, if you get the MBR disk over 2TB, the rest of unallocated space will be out of control. Check your disk size and format first when you cannot create new simple volume from unallocated space with Disk Management.

How to solve?

In order to make the most use of unallocated space, you’re recommended to convert MBR to GPT. Two ways are available here but please pay attention that not all hard drive fit GPT such as Windows XP, etc! Check it out in advance.

Method 1: reinitialize via Disk Management

As Disk Management is one built-in tool in Windows system, you can use it to reinitialize the disk to GPT. However, in this case, you need to erase the disk, which may lead to data loss. You could do backup first while the whole process is too time-consuming. What’s more, there are many invisible files or folders that you can’t copy.

Method 2: convert disk via AOMEI Partition Assistant

Employing a third-party partition software like AOMEI Partition Assistant is one ideal solution. It helps you perfectly solve “unallocated space cannot create partition” without losing data. Let’s see how it works.

Install and launch AOMEI Partition Assistant. Right click the disk you need to convert. Select “Convert to GPT Disk”.

Convert Data Disk To GPT

A pop-up window will ask for your confirmation. Click “OK”.

OK To GPT Data Disk

Then, click “Apply” to execute. Reboot will be required if there’s any running program.

Apply To GPT Data Disk

When conversion is completed, you’re able to create partition, extend partition with unallocated space and so on with Partition Assistant as well.