The MBR2GPT Disk Conversion Tool in Windows 10

Windows 10 introduces a new MBR2GPT Disk Conversion Tool using which you can safely and non-destructively convert a Windows 10 computer from legacy BIOS to UEFI disk partitioning, as well as automate the conversion as part of your in-place upgrade process from Windows 7 to Windows 10. Moreover, unlike Wipe & Load methods, all of this can be achieved without having to move your data off the disk.

MBR2GPT Disk Conversion Tool

mbr2gpt MBR2GPT Disk Conversion Tool

MBR2GPT.exe, located in the System32 folder, is a command line tool that will help you convert a disk from Master Boot Record (MBR) to GUID Partition Table (GPT) partition style without modifying or deleting data on the disk. You can run the tool from Windows PE (Windows Preinstallation Environment) command prompt, as well from the Windows 10 OS.

Using MBR2GPT.exe you can convert any attached MBR-formatted disk to GPT, including the system disk, within the Windows PE environment as well as withing the operating system. You can also use the tool to convert an MBR disk with BitLocker-encrypted volumes.

Operating system disks running Windows 10 v1507, v1511, and v1607 and later can also be converted, provided you are running it from Windows 10 v1703 and perform an offline conversion.

However, offline conversion of system disks with earlier versions of Windows installed, such as Windows 7, Windows 8 and Windows 8.1 are not officially supported – you will have to upgrade to Windows 10 first, then perform the MBR to GPT conversion.

To convert MBR to GPT using the built-in MBR2GPT.exe tool:

Boot into Advanced Startup Options screen > Troubleshoot > Advanced options > Command Prompt.

Execute the following command to validate that the drive meets the requirements:

mbr2gpt /validate

Execute the following command to convert the drive from MBR to GPT:

mbr2gpt /convert

Restart your computer.

Do note that MBR2GPT can only be used from the Windows Preinstallation Environment. To use it ffrom your Desktop, you have to use /allowFullOS to override.

You can read all about this new MBR2GPT Disk Conversion Tool, including the syntax to be used here at Microsoft.

Posted by on , in Category Windows with Tags
Anand Khanse is the Admin of, a 10-year Microsoft MVP Awardee in Windows (2006-16) & a Windows Insider MVP. Please read the entire post & the comments first, create a System Restore Point before making any changes to your system & be careful about any 3rd-party offers while installing freeware.


  1. Adam Hill

    Is MBR2GPT available for Windows 10 Home?

  2. Redshiftza

    Why would anyone wnat to convert to a GPT disk. When you motherboard fails or you want to move it to another device or computer then you will no longer have access to the disk. I call BS!

  3. Crackr Boom

    i still got an error when validating the disk,

  4. Ryan JL

    You need to have GPT to install any updates. Thus, I cannot install any updates. Thus, I cannot install 1703. Thus, I cannot get this tool. I need the tool to update the system to get the tool!

  5. Kelly Bancroft

    Has anyone tried the tool? I’m curious how long it actually takes to convert a drive.

  6. Yukthi Lochana

    yep, it only takes several seconds as I can remember, converts without much of a hassle.Just make sure to run the validation before conversion and make sure you have less than 4 partitions on the drive in order to create the EFI partition before the MBR to GPT conversion.

  7. Yukthi Lochana

    you don’t 🙂 I converted my drive after getting the v1703 build on my laptop. Or you can download the Windows PE on a bootable drive/disk, and run the tool on the desired drive on Win PE.

  8. Yukthi Lochana

    How many partitions do you have on the drive? I got an error due to having the maximum no. of partitions allowed on MBR format, (which is 4) it stops the tool from creating the EFI partition which is required to be done before the conversion.

  9. thecodye

    This is simply nonsense and untrue. Unless the drive is using some kind of encryption with a TPM on the motherboard (like bitlocker), you can use a GPT drive on any modern motherboard, or even older ones.

  10. yeah, took about 20 seconds for me, but I have a 80GB drive for windows so it could possibly take longer on bigger drives… I also had to run it twice, it failed the first time round and worked the second try

  11. I laughed so hard when I read this because I’m in this same situation on Windows 10 N. I have an external USB SSD with MBR and do not have the tool available. I tried creating a Windows PE USB drive, and after I booted into it, the tool does not exist (likely because when creating Windows PE it pulls files from your source computer, and mine doesn’t have the tool). Why doesn’t MS just add a download for this tool?

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