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Convert a GPT disk into an MBR 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). MBR disks don't support more than four partitions on each disk. The MBR partition method isn't recommended for disks larger than 2 terabytes (TB).

You can change a disk from GPT to MBR 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 a GPT disk

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

  1. Before conversion, back up or move the data on the GPT 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 GPT 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 GPT disk to convert to the MBR format, and select Convert to MBR Disk.

The process notifies you when the conversion completes.

Use the command line to convert a GPT 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 GPT 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 GPT disk for conversion by cleaning (deleting) any partitions or volumes.

    Note

    If the GPT 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 GPT disk number that you want to convert to MBR format.

    2. At the DISKPART prompt, enter select disk <disk-number>, where <disk-number> is the GPT 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 mbr to convert the GPT disk to the MBR 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 GPT or MBR 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 mbr Converts an empty basic disk with the GPT partition format into a basic disk with the MBR partition format.