By Emily / Last Updated April 21, 2022

Convert to GPT Disk Grayed Out in Windows Disk Management

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 is able to 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 the Microsoft declaimed that upgrading from Windows 10 to Windows 11 via the "Check for Update" feature requires the 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.

Convert to GPT Greyed Out

Why the "Convert to GPT Disk" is greyed out and how to solve it?

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.

Convert to GPT

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:

Windows Setup

▶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

Best way to evade "Convert to GPT Disk" greyed out issue (without data loss)

No matter which solution mentioned above you finally use, you will have to delete all partitions and data befor 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 without losing any data. Besides, it is also able to directly convert system disk 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, resize partitions, move partitions, merge partitions, make bootable devices, and more. AOMEI Partition is fully compatible with Windows 11/10, 8/8.1, 7, Vista, and XP.

It's available to download the demo version of AOMEI Partition Assistant Professional to have a try!

Download Pro Demo Win 11/10/8.1/8/7/XP
Secure Download

Step 1. Install and launch AOMEI Partition Assistant Professional. Right-click the disk you want to convert and select "Convert to GPT Disk".

Convert Data Disk to GPT

Step 2. Click "OK" to confirm the operation.

OK to GPT Data Disk

Step 3. You can now preview the conversion. To apply the changes, please click "Apply" on the top left of the toolbar.

Apply to GPT Data Disk

★Tips:
If you encounter issues - convert to GPT  grayed out in Windows Server 2003, 2008, 2012, 2016 ,2019 and 2022, then check out AOMEI Partition Assistant Server Edition.
When converting a system disk between MBR and GPT styles, if you want to guarantee that the system will be bootable then you will need to enter the BIOS and change the boot mode after the conversion has finished. For more information on BIOS and EFI (UEFI), please refer to GPT formatted disk legacy boot not supported.
When converting between MBR and GPT disks on Laptops, please make sure that the battery will last longer than the conversion process, we recommend you plug your Laptop into a wall socket.
To protect your data, please do not stop/terminate the process once it has begun.

Conclusion

The majority of Windows users will find themselves needing to convert from MBR to GPT, however, there may be the odd circumstance where you need to the 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.