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Convert an MBR disk into a GPT disk

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Master Boot Record (MBR) disks use the standard BIOS partition table. GUID partition table (GPT) disks use the Unified Extensible Firmware Interface (UEFI). One advantage of GPT disks is that you can have more than four partitions on each disk. GPT is also required for disks larger than 2 terabytes (TB).

You can change a disk from MBR to GPT partition format as long as the disk contains no partitions or volumes.

Important

  • Before you convert a disk, back up any data on the disk, and close any programs that access the disk.
  • You must be a member of the Backup Operators or Administrators group, at minimum, to convert a disk.

Use Disk Management to convert an MBR disk

To complete the disk conversion by using Disk Management, follow these steps.

  1. Before conversion, back up or move the data on the MBR disk.

  2. In the search box on the taskbar, enter Create and format hard disk partitions to launch Disk Management.

  3. Delete all partitions and volumes on the MBR disk.

    • For each partition or volume, select and hold (or right-click) the item, and select Delete Partition or Delete Volume.

  4. Select and hold (or right-click) the MBR disk to convert to the GPT format, and select Convert to GPT Disk.

The process notifies you when the conversion completes.

Use the command line to convert an MBR disk

To complete the disk conversion from the command line with the diskpart disk partition process, follow these steps.

  1. Before conversion, back up or move the data on the MBR disk.

  2. Open an elevated command prompt: select and hold (or right-click) Command Prompt, and select Run as Administrator.

  3. At the prompt, enter diskpart to initiate the disk partition process.

  4. Prepare the MBR disk for conversion by cleaning (deleting) any partitions or volumes.

    Note

    If the MBR disk doesn't have any partitions or volumes, skip to the last step to apply the conversion.

    1. At the DISKPART prompt, enter list disk. Make a note of the MBR disk number that you want to convert to GPT format.

    2. At the DISKPART prompt, enter select disk <disk-number>, where <disk-number> is the MBR disk number to convert.

    3. At the DISKPART prompt, enter clean to delete all partitions and volumes on the disk.

  5. At the DISKPART prompt, enter convert gpt to convert the MBR disk to the GPT partition format.

The diskpart process notifies you when the conversion completes.

Review diskpart commands

The following table shows a summary of the commands for the diskpart process.

Command Description
list disk Displays a list of disks and information about them, such as their size and the amount of available free space. The command also shows whether the disk is a basic or dynamic disk, and whether it uses the MBR or GPT partition format. In the list of results, the disk marked with an asterisk (*) has the current focus for entered commands.
select disk <disk-number> Selects the specified disk, where <disk-number> is the disk number that you want to select. The command also gives the current focus to the specified disk.
clean Removes all partition or volume sections from the disk that has the current focus.
convert gpt Converts an empty basic disk with the MBR partition format into a basic disk with the GPT partition format.

Use the MBR2GPT conversion tool

As an alternate approach, you can use the MBR2GPT.EXE tool to convert the MBR disk to the GPT partition format. Keep in mind that the tool can be more complicated to use than the diskpart process. For details, see Convert MBR partition to GPT.