How to Convert MBR to GPT Without Losing Data in Windows

When upgrading to a new PC or enabling UEFI on your PC, you may receive a message that the drive needs to be converted into GPT. To resolve this, this post will share how to convert MBR to GPT without losing data. We will also share easy ways to convert, but it will ensure data loss, which is suitable if you have a backup or set up a new PC.

What are MBR and GPT?

A partition table is required to keep track of what is on each of your hard drives. Windows can find the files you require by using the partition table, which describes the partitions (parts) of the drive. Depending on your operating system and firmware, Windows uses the GUID Partition Table (GPT) or the Master Boot Record (MBR).

Let us consider the variations between MBR and GPT and why some systems favor one over the other.

MBR

MBR is the most established of the two, so it works with a greater range of systems. MBR was created for IBM PCs and, as a result, was the default partition table for Windows machines for a significant period.

The Master Boot Record, which contains the bootloader for the operating system and details about the drive partitions, gets its name from being at the very beginning of the drive. Drives that are up to 2TB in capacity can only use MBR.

GPT

GPT is the more recent of the two. GPT is closely related to UEFI, the firmware solution that replaces the outdated BIOS option. The GUID Partition Table assigns every partition on your drive a globally unique identifier (GUID), a 128-bit number that identifies only your hardware.

Compared to MBR drives, GPT drives have fewer restrictions. GPT drives have the potential to be significantly larger than MBR drives (with the right settings, a theoretical 256TB drive would work). GPT disks can have up to 128 distinct partitions on a Windows system without an extra partition. They simplify the recovery by storing several copies of the boot data across many partitions compared to the MBR drive.

System Requirement for GPT

• A UEFI-based system is necessary for 64-bit Windows 11, 10, 8,/8.1, 7, and Vista to boot from a GPT drive.
• A UEFI-based system is necessary for 32-bit Windows 10 and 8/8.1 to boot from a GPT drive. Windows 11 has no 32-bit edition.
• A GPT drive can be read from and written to by all of the Windows versions mentioned.

How to Convert MBR to GPT Without Losing Data in Windows

Without changing or erasing any of the data on the drive, MBR2GPT.EXE converts a disk from the Master Boot Record (MBR) partition style to the GUID Partition Table (GPT) partition style. Although the program intends to launch from a Windows Preinstallation Environment (PE) command prompt or Advanced Recovery, it can also run from the entire Windows operating system (OS) using the /allowFullOS option.

Features of MBR2GPT includes:

• You can change any associated system disk with an MBR format to a GPT partition.
• If protection has been suspended, it can convert an MBR drive with BitLocker-encrypted volumes.
• It can convert operating system disks that have earlier versions of Windows 10 installed.
• If your task sequence uses Windows PE version 1703 or later, you can use Configuration Manager or MDT to change an operating system drive from MBR to GPT.

Here is a complete guide in the form of a video on this

How To Use MBR2GPT

The conversion process is non-destructive and will only take minutes. Earlier, you needed to copy your data to an external storage device, reinstall windows and then restore the data. With MBR2GPT, the conversion is done by applying the GPT components to an MBR disk without modifying the existing partitions in the file systems, allowing the data to remain intact. So here is how to use the tool:

• Open search using Win + S.
• Type Disk Management, and click on Format and Harddisk partitions listing to open it
• The Disk Management will display all the connected storage devices and volumes.
• Right-click on the system disk (where Windows is available) and choose Properties.
• Next, click the Volumes tab, and we can find that the system uses the MBRT Partition Style or its GPT. If its GPT, you must change the Boot mode from BIOS.
• To perform the conversion, boot the PC to Windows Advanced Recovery (Windows Settings > System > Recovery > Advanced Startup)
• Once in recovery, Go to Troubleshoot > Command Prompt.
• Navigate to the MBR2GPT tool located under the C:\Windows\System32 directory.
• To find the usage information, type the command line mbr2gpt /validate, and in case the disk does not meet any requirements, for example, if the disk is already GPT, the tool will return an error.

Next, we are going to convert the disk using the convert option. This will typically shrink the Windows partition and create a new system partition in the freed-up space.

• Type the command line mbr2gpt /convert. The conversion will only take a few seconds.
• Once done, reboot the system into BIOS.
• E.g., change the Boot Mode from Legacy Mode to UEFI. The settings may vary for each PC manufacturer. 

In Disk Management, you will file that the Partition Style has changed to GPT. System information will show that Windows now boots in UEFI mode and Secure Boot State is active.

How to Convert MBR to GPT (with Data Loss)

If you have a proper backup in place, preferably System Image, or are setting up a new PC, then it’s best to use these tools.

1. DiskPart Tool
2. Disk Management

Also, you will need to connect it to a working PC and then use these tools.

1] Convert MBR to GPT Using DiskPart Tool

Use the steps below to convert an empty MBR drive to a GPT disk using the Diskpart tool. Also, ensure to press Enter after typing each command.

• Press Win + X and click on Command Prompt (Admin) or Windows Terminal (Admin)
• Type diskpart to list the disks connected to the PC.
• Type list disk at the DISKPART prompt. Make a note of the conversion-related disk number.
• At the DISKPART prompt, type select disk <disknumber>.
• Type clean at the DISKPART prompt.
• Type convert gpt at the DISKPART prompt and press Enter

You can execute the last step after the first if there are no partitions.

2] Convert MBR to GPT Disk with Disk Management 

The basic GPT disk you intend to change into an MBR disk should have all of its volumes backed up or moved.

• Type diskmgmt.msc in the Run prompt(Win + R), open it with admin permission using Shift + Enter.
• If the drive has any partitions or volumes, you should right-click each and select Delete Volume from the menu.
• Click Convert to MBR disk from the context menu of the GPT disk you wish to convert to an MBR disk.

Conclusion

Your old MBR drive has been changed into a GPT drive, giving you more flexibility in how you use your disk. You will discover that you have more control over your system firmware once you change your partition table and convert it from BIOS to UEFI. After all, enabling more control and sophisticated options over your hardware was one of the key reasons UEFI was introduced.