Master Boot Record (MBR) disks use the legacy BIOS partitioning scheme (also known as partition style) and supports up to four primary partitions per disk. MBR is limited to disks of 2 TB or smaller and isn't recommended for larger drives. GUID Partition Table (GPT) disks use the modern Unified Extensible Firmware Interface (UEFI), supports more than four partitions, and can manage disks larger than 2 TB.
You can convert a disk's partition style only if it doesn't contain any partitions or volumes. Make sure to delete all existing partitions or volumes before attempting to change the disk's format.
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 Administrators group (or have equivalent privileges) to convert a disk.
Convert a disk
You can convert your disk using either the Disk Management tool or the command line. Follow these steps for your method of choice.
Before you convert partition styles, back up or move the data off the disk.
Select Start, type diskmgmt.msc, then select Enter.
Right-click on the volume pertaining to your GPT disk.
Select Delete Volume, then select Yes. Repeat this step for all volumes on the GPT disk.
Right-click on the GPT disk, then select Convert to MBR Disk.
To verify the conversion process, right-click on your disk, select Properties, select the Volumes tab, and check the partition style information.
Before you convert partition styles, back up or move the data off the disk.
Open an elevated command prompt window, type diskpart, then select Enter.
Prepare your disk for conversion by cleaning (deleting) any partitions or volumes.
Note
If your disk doesn't have any partitions or volumes, skip to step 6 to convert your disk.
Type list disk and hit Enter. Make a note of the disk number that you want to convert.
Type select disk, provide the disk number you want to convert, then hit Enter.
Type clean to delete all partitions and volumes on the disk.
To convert GPT to MBR, type convert mbr, then hit Enter.
To convert MBR to GPT, type convert gpt, then hit Enter.
You're notified when the conversion process completes.
Before you convert partition styles, back up or move the data off the disk.
Open an elevated PowerShell window.
Prepare your disk for conversion by cleaning (deleting) any partitions or volumes.
Note
If your disk doesn't have any partitions or volumes, skip to step 3 to convert your disk.
To list all disks, run the following command:
Get-Disk
Note the disk number you want to convert.
To remove all partitions and volumes from the disk, run the following command. Replace <Disk Number> with the disk number you noted earlier:
Clear-Disk -Number <Disk Number> -RemoveData -Confirm:$false
To convert the partitioning style, run the following command:
For MBR to GPT conversion:
Initialize-Disk -Number <Disk Number> -PartitionStyle GPT
For GPT to MBR conversion:
Initialize-Disk -Number <Disk Number> -PartitionStyle MBR
Note
Once a disk is initialized, you can't convert it to another partition style without first running the Clear-Disk cmdlet again.
To verify the conversion process, run the following command and check the Partition Style column:
Get-Disk
See also