To make it easy, ‘master boot record’ (MBR) and ‘GUID partition table’ (GPT) are the partition table styles, used by the hard disk drives to store information about the partitions. MBR is the old standard for managing partitions while GPT is current standard. GPT has got few advantages over MBR. While we only see partitions in a hard disk drive, there is also MBR or GPT area used by disk drives that define how the disk drive will be managed. MBR disks use the standard BIOS partition table and GPT disks use unified extensible firmware interface (UEFI). MBR disks do not support more than four primary partitions on each disk and MBR partition method is not recommended for disks larger than 2 terabytes. You can change a disk drive from GPT to MBR partition style or MBR to GPT partition style by using any of the methods in this guide.
Warning: First of all keep in mind that you are changing partition table of an empty disk drive. All current data and partitions from the disk drive will be lost during partition table change. Backup your data or whole partitions at some other location before changing partition table style.
In two screenshots above, Gparted was used to convert GPT to MBR. Below are several methods and software that can be used for this conversion.
By Using Live Disk
SystemRescueCd comes with ‘GNU Parted‘ and ‘GParted‘. Gparted lets you edit partitions and partition tables. In screenshots above I used Gparted to convert partition table from GPT to MBR. Burn SystemRescueCd to CD or USB disk and boot computer from live CD or live USB disk. You will have to press ‘Enter’ once and then type ‘startx‘ and then hit ‘Enter’ once more to see the graphical interface of this live Linux. Click ‘Menu’ (its like start button in Microsoft Windows) and select ‘Run Program’. Type ‘gparted’ and hit ‘Enter’ to launch ‘gparted’. You can also click at the third icon at the bottom left. First is ‘menu’, second is ‘terminal’ and the third is ‘gparted’.
Warning: You can also use GParted live disk. While creating live USB disk for Gparted, DO NOT RUN makeboot.bat from your local hard drive on Microsoft Windows. Doing so could cause your windows OS not to boot.
Once you have Gparted running, you can go to Device > Create Partition Table from above main menu. Select new partition table type (in my case I selected msdos) and click apply. GPT will be converted to MBR.
On Microsoft Windows
You can change partition table type in Microsoft Windows by using ‘Windows interface’ or ‘command line’. In Windows interface go to Disk Management. Right click at ‘My Computer’ or ‘Computer’ icon and select Manage. Click at Disk Management. Right click at the disk, not at the disk volume. Select Properties and go to Volumes tab. In the details there, you can see the partition style. In screenshots below its ‘MBR’.
To change the partition style to GPT or MBR, you will have to delete current volumes (partitions) on the disk drive. You can do so by right clicking on partition and selecting ‘Delete Volume’. Before that, copy data from those volumes. So the disk drive must be empty with no partitions in it, in order to convert the partition table type. After that, just select disk from left side and click Convert to GPT Disk or Convert to MBR Disk depending upon your requirement.
If you want to convert partition table type via command prompt, follow instructions below:
Type cmd in start. Right click at cmd.exe and select Run as Administrator.
If the disk drive is empty (with no partitions in it), type diskpart and hit ‘Enter’, type convert mbr or convert gpt, hit ‘Enter’.
If you have to delete partitions yet, type diskpart and hit ‘Enter’. type list disk and hit ‘Enter’. Make note of the ‘disk number’ you want to delete. Type select disk
Note: convert gpt will convert ‘MBR Disk’ to ‘GPT Disk’ while convert mbr will convert ‘GPT Disk’ to ‘MBR Disk’.
Linux usually has got ‘GParted‘ with it. If not, you can install ‘Gparted’ easily.
For Ubuntu, you can run following commands in terminal to install GParted.
sudo apt-get update sudo apt-get install gparted
You can also browse to GParted app page on Ubuntu apps directory to get this app. You can download GParted from getdeb to install it in Linux. Download the getdeb package, then double-click to install it via pop-up Ubuntu Software Center. It will add getdeb repository to your system. Once you have got the GParted in Linux, its easy to convert disk drive partition table type as mentioned above in the ‘Gparted with Live Disk’ section.
You can also use gDisk. Install the gDisk by using following commands in terminal:
sudo apt-get update sudo apt-get install gdisk
Type sudo gdisk in terminal to and hit ‘Enter’. Now you can use gDisk as a superuser. Press r and hit ‘Enter’ to switch to the recovery and transformation options. Press g and hit ‘Enter’ to select the option to convert GPT to MBR on Linux. Press 0 and hit ‘Enter’ to convert GPT to MBR on the primary partitions. Press y and hit ‘Enter’ to finalize and exit.
Notes: Disk drive should be unmounted (in case of Linux) to convert its partition table type. Disk drive should be empty and should not have any partitions in it. It is best to use a live disk with partition editor to convert partition table type. Alternatively you can plug the disk drive (that is to be converted for partition table type) as an external disk drive to computer and proceed with the conversion.
If you want to preserve data and partitions while MBR/GPT conversion, there are ways to do so.
Convert MBR or GPT Without Data Loss
GptGen is free for Microsoft Windows and it can convert GPT or MBR without losing data on disk drives. GptGen is a bit complicated to use because its a command based utility.
Syntax of GptGen is following:
gptgen [-w] \\.\physicaldriveX
Where X is the drive number that you can get by using list disk command of the DISKPART utility in DOS (mentioned above). The -w option makes gptgen write the generated GUID partition tables to the disk.
Disk Partition Magic Software by Macrorit is a full featured disk drive management software for Microsoft Windows that can also convert GPT or MBR without data loss.