Change a Master Boot Record Disk into a GUID Partition Table Disk

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Applies To: Windows 7, Windows Server 2008 R2

Master boot record (MBR) disks use the standard BIOS partition table. GUID partition table (GPT) disks use 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.

You can change a disk from MBR to GPT partition style as long as the disk does not contain any partitions or volumes.

You cannot use the GPT partition style on removable media, or on cluster disks that are connected to shared SCSI or Fibre Channel buses that are used by the Cluster service.

Backup Operators or Administrator is the minimum membership required.

Note
Before you convert disks, close any programs that are running on those disks.

Changing a master boot record disk into a GUID partition table disk

• Using the Windows interface
  
• Using a command line
  

To change a master boot record disk into a GUID partition table disk using the Windows interface

1. Back up or move the data on the basic master boot record (MBR) disk you want to convert into a GUID partition table (GPT) disk.
2. If the disk contains any partitions or volumes, right-click any volumes on the disk and then click Delete Partition or Delete Volume.
3. Right-click the MBR disk that you want to change into a GPT disk, and then click Convert to GPT Disk.

To change a master boot record disk into a GUID partition table disk using a command line

1. Back up or move the data on the basic master boot record (MBR) disk you want to convert into a GUID partition table (GPT) disk.
2. Open an elevated command prompt (right-click Command Prompt, and then click Run as Administrator) and type diskpart. If the disk does not contain any partitions or volumes, skip to step 6.
3. At the DISKPART prompt, type list disk. Make note of the disk number you want to convert.
4. At the DISKPART prompt, type select disk <disknumber>.
5. At the DISKPART prompt, type clean.
   

   Important
   Running the clean command will delete all partitions or volumes on the disk.

6. At the DISKPART prompt, type convert gpt.

 

Value	Description
list disk	Displays a list of disks and information about them, such as their size, amount of available free space, whether the disk is a basic or dynamic disk, and whether the disk uses the master boot record (MBR) or GUID partition table (GPT) partition style. The disk marked with an asterisk (*) has focus.
select diskdisknumber	Selects the specified disk, where disknumber is the disk number, and gives it focus.
clean	Removes all partitions or volumes from the disk with focus.
convert gpt	Converts an empty basic disk with the master boot record (MBR) partition style into a basic disk with the GUID partition table (GPT) partition style.

Additional references

• Command-line syntax notation