Sometimes, the "Convert to GPT Disk" greyed out issue occurs in Windows Disk Management. Here we will tell why you are unable to convert MBR to GPT, as well as how to get it solved easily.
As we’ve learned before, the maximum size of an MBR-style disk is limited to 2TBs and four primary partitions. A disk in the GPT style can hold up to 128 primary partitions and more than 16 million TBs of data. When compared with MBR, GPT disks have greater compatibility with modern hardware and systems as they use the newer UEFI boot mode. And now Microsoft declaimed that upgrading from Windows 10 to Windows 11 via the "Check for Update" feature requires UEFI and GPT, people who want to experience a new system might have to select GPT disk.
However, when you are trying to convert disk to GPT via Disk Management, a partition tool embedded in Windows, you might find the “Convert to GPT Disk” option is grayed out, as seen in the screenshot below.
Why are you unable to convert MBR to GPT? The most important reason is that there are existing partitions on the disk. The Disk Management can only convert an empty non-system disk from MBR to GPT, or GPT to MBR. In such a case, you have to back up all important data on the disk, delete all the partitions and then start the conversion. After deleting every partition, you will find the “Convert to GPT” option will no longer be grayed out and you can convert it successfully.
The above solution only works when you are trying to convert the data disk since the system disk cannot be converted to GPT or MBR via Windows Disk Management. That's because you are not allowed to delete the system partition when the Windows is running. Under this situation, you can turn to DiskPart.exe tool, which requires you to boot PC from installation media, press Shift+F10 at the Windows Setup screen to launch the Command Prompt window, and execute the following commands:
▶list disk ( This will show you all the disks on your computer. Make note of the disk number that you want to convert to GPT. In this guide we will use disk 1 as an example.）
▶select disk n (Diskpart will remind you that the disk n is selected)
▶clean (remove all partitions on the target disk)
▶convert gpt
No matter which solution mentioned above you finally use, you will have to delete all partitions and data before being able to convert MBR to GPT. So, now we would like to share the best solution to Disk Management "Convert to GPT" greyed out problem. That is turning to AOMEI Partition Assistant Professional, a safe and powerful partition manager that can help you convert MBR and GPT without deleting any partitions or losing any data. Besides, it is also able to directly convert system disks without entering WinPE environment if the computer can boot up successfully.
Compared with Disk Management, AOMEI Partition Assistant is far more powerful and able to complete a whole range of advanced disk management features such as directly converting to GPT/MBR, resizing partitions, moving partitions, merging partitions, making bootable devices, and more. AOMEI Partition is fully compatible with Windows 11/10, 8/8.1, and 7.
It's available to download the demo version of AOMEI Partition Assistant Professional to have a try!
Step 1. Install and launch AOMEI Partition Assistant Professional. Right-click the disk you want to convert and select "Convert to GPT" or click the disk and choose "Convert to GPT" from the right menu.
Step 2. Click "OK" to confirm the operation.
Step 3. You can now preview the conversion. To apply the changes, please click "Apply" on the top left of the toolbar.
The majority of Windows users will find themselves needing to convert from MBR to GPT, however, there may be odd circumstances where you need to do the reverse (GPT to MBR). Usually, this is because they are using Windows 2000, Windows 2003 32-bit, or Windows XP 32-bit as these operating systems don’t support GPT formatted disks. If you do use a GPT disk with these OS’s, then it will show up as a "GPT protective partition" and you will be unable to access your data. Fortunately, AOMEI Partition Assistant is also able to help you convert GPT to MBR without losing any of your data.
1. Why is the option to "Convert to GPT Disk" grayed out in Windows Disk Management? The option to convert a disk to GPT (GUID Partition Table) may be grayed out in Windows Disk Management if the disk is currently in use, has partitions that are not supported by GPT, or if the disk is smaller than 2TB.
2. How can I fix the issue of "Convert to GPT Disk" being grayed out? To resolve this issue, you can try to make sure that all partitions on the disk are deleted, remove any volumes or drive letters assigned to the disk, or disconnect the disk from the system temporarily. You can also use third-party partition management software to convert the disk to GPT.
3. Are there any limitations to converting a disk to GPT in Windows Disk Management? Yes, there are limitations to converting a disk to GPT in Windows Disk Management. For example, you cannot convert a system disk to GPT without losing data, and you cannot convert a disk to GPT if it contains partitions that are not supported by GPT.
