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How to convert MBR to GPT drive to switch BIOS to UEFI on Windows 10

Convert MBR to GPT on Windows 10
Convert MBR to GPT on Windows 10 (Image credit: Windows Central)

When you want to switch firmware type from the Basic Input/Output System (BIOS) to Unified Extensible Firmware Interface (UEFI) without modifying the current installation or deleting the data stored on the drive, or you plan to upgrade Windows 10 to Windows 11, you can convert the drive using a Master Boot Record (MBR) to a GUID Partition Table (GPT) partition style using the "MBR2GPT" tool.

BIOS is a piece of code that resides on the motherboard that connects the hardware and software. This code has been around for a long time, and while it worked well, it was never designed for modern hardware, and it had many limitations, including limitations to partitions smaller than 2TB.

UEFI is the new firmware type designed to replace the old BIOS style. It introduces additional features, including support for partitions larger than 2TB and faster startup, sleep, resume, and shutdown times. Also, it unlocks new security features available on Windows 11 and Windows 10. For instance, "Secure Boot" is a feature that can protect a device's startup process from malicious programs, and now it's a prerequisite to install Windows 11. "Device Guard" gives you more advanced controls for app access, and "Credential Guard" can help prevent pass-the-hash attacks.

In this Windows 10 guide, we will walk you through the steps and information to use the Microsoft MBR2GPT command-line tool to convert a drive from MBR to GPT partition style, to switch from BIOS to UEFI mode on your device, and enable Secure Boot correctly.

Warning: This is a non-destructive process, but it's still recommended to make a full backup of your PC before proceeding in case something goes wrong and you need to recover your setup.

How to convert a drive from MBR to GPT on Windows 10

Unlike older methods requiring a backup of your data and reinstalling Windows, the MBR2GPT tool makes it easy to change the partition style quickly. When using this tool, the conversion process adds the GPT components to the MBR partition without modifying the existing partition and maintaining the data untouched.

The best approach is switching to UEFI and performing a clean install of Windows 11. However, if you already have a Windows 10 installation that you want to upgrade, you can convert the drive to change the system firmware settings properly. Otherwise, the device will no longer start correctly.

Check MBR or GPT partition style

Before making system changes, check the current settings to see whether the system is set to MBR or GPT using these steps:

  1. Open Start.
  2. Search for Disk Management and click the top result to open the experience.
  3. Right-click the drive (where Windows 10 resides) and select the Properties option.

Source: Windows Central (Image credit: Source: Windows Central)
  1. Click on the Volumes tab.
  2. Under the "Partition style" field, if the field reads GUID Partition Table (GPT), the drive does not need conversion, but if you see the Master Boot Record (MBR) label, you will need to use the conversion tool.

Source: Windows Central (Image credit: Source: Windows Central)
  1. Click the Cancel button.

Once you complete the steps, you can change the partition style on the computer.

Also, if you need to change the partition, check your device manufacturer's support website to find out whether the hardware includes support for UEFI before using these instructions.

Convert MBR to GPT partition style (offline)

To convert a drive using MBR to GPT on Windows 10, use these steps:

  1. Open Settings.
  2. Click on Update & Security.
  3. Click on Recovery.
  4. Under the "Advanced startup" section, click the Restart now button.

Source: Windows Central (Image credit: Source: Windows Central)
  1. Click the Troubleshoot option.

Source: Windows Central (Image credit: Source: Windows Central)
  1. Click on Advanced options.

Source: Windows Central (Image credit: Source: Windows Central)
  1. Click the Command Prompt option.

Source: Windows Central (Image credit: Source: Windows Central)
  1. Select your administrator account and sign in (if applicable).
  2. Type the following command to validate the drive's requirements and press Enter:mbr2gpt /validateQuick tip: The mbr2gpt.exe is located in the "System32" folder inside the "Windows" folder. If you want to see all the available options, use the mbr2gpt /? command.

Source: Windows Central (Image credit: Source: Windows Central)
  1. Type the following command to convert the drive from MBR to GPT and press Enter:mbr2gpt /convert

Source: Windows Central (Image credit: Source: Windows Central)
  1. Click the Close button.
  2. Click the Turn off your PC option.

After you complete the steps, the tool will validate the drive and create an EFI system partition (ESP). The process will also insert the UEFI boot files and GPT components into the partition. The tool will update the Boot Configuration Data (BCD), and the previous drive letter will be added to the drive.

Convert MBR to GPT partition style (online)

It's always recommended to use the MBR2GPT tool offline to avoid potential problems. However, you can also run it when the system is operational.

To convert a drive from MBR to GPT on Windows 10, use these steps:

  1. Open Start.
  2. Search for Command Prompt, right-click the top result, and select the Run as administrator option.
  3. Type the following command to validate the drive and press Enter:mbr2gpt /validate /allowFullOS

Source: Windows Central (Image credit: Source: Windows Central)
  1. Type the following command to convert the drive to GPT and press Enter:mbr2gpt /convert /allowFullOS

Source: Windows Central (Image credit: Source: Windows Central)

Once you complete the steps, the command-line tool will reduce the size of the primary partition and change it from MBR to GPT.

MBR2GPT return codes

If the processes are completed successfully, the return code would be "0," but if the process fails, you may see one of the 11 error codes:

Return codeDescription
1User canceled the conversion.
2Internal error.
3Initialization error.
4Invalid command-line parameters.
5Error on the geometry and layout of the selected disk.
6One or more volumes on the disk are encrypted.
7Geometry and layout of the disk don't meet requirements.
8Error while creating the EFI system partition.
9Error installing boot files.
10Error while applying GPT layout.
100Successful conversion, but some boot configuration data didn't restore.

MBR2GPT important details

You can use the MBR2GPT tool on a traditional hard drive (HDD), solid-state drive (SSD), or an M.2 drive with virtually any version of Windows 10, but you must run the tool from a Windows 10 (version 1703 or later) installation.

When dealing with a drive using file encryption with BitLocker, you must first suspend the encryption before following the outlined instructions.

While MBR-style drives can have up to four primary partitions, the drive you want to convert can't have more than three partitions because one additional allocation is required to create the UEFI partition.

Finally, Microsoft designed the tool to convert drives running Windows 8.1, 7, or from an older version, but you can always upgrade the installation to the latest release of Windows 10 and then use the tool to convert from MBR to GPT.

How to change the firmware mode from BIOS to UEFI

After converting the drive to the GPT style, the computer will no longer start until you change the firmware type from BIOS to UEFI in the motherboard.

Typically, this process requires hitting one of the function keys (F1, F2, F3, F10, or F12), Esc, or Delete key as soon as you start the device. However, since these options are always different, it's best to check your device manufacturer's support website for more specific details.

On the firmware interface, find the "Boot" menu, enable the UEFI option, save the changes, and then the computer should start normally.

Also, if you plan to upgrade the device to Windows 11 while in the UEFI settings, open the boot or security settings page, make sure to enable the "Secure Boot" option, and exit the firmware saving the changes.

Check GPT partition style

To confirm the device is using a GPT partition style, use these steps:

  1. Open Start.
  2. Search for Disk Management and click the top result to open the app.
  3. Right-click the main drive and select the Properties option.

Source: Windows Central (Image credit: Source: Windows Central)
  1. Click on the Volumes tab.
  2. Under the "Partition style" field, the information should now read GUID Partition Table (GPT).

Source: Windows Central (Image credit: Source: Windows Central)

After you complete the steps, if the partition is running using the correct partition style, you only need to check whether the device uses the UEFI firmware mode.

Check UEFI firmware

To confirm the computer is in UEFI mode and Secure Boot is turned on, use these steps:

  1. Open Start.
  2. Search for msinfo32 and click the top result to open the System Information app.
  3. Click on System Summary on the left pane.
  4. Check the "BIOS Mode," which now should read UEFI.

Source: Windows Central (Image credit: Source: Windows Central)
  1. Check the "Secure Boot State" information, which now should read On.

Once you complete the steps, if the System Information displays the mode as "UEFI," you have successfully switched the firmware type.

More Windows resources

For more helpful articles, coverage, and answers to common questions about Windows 10 and Windows 11, visit the following resources:

Mauro Huculak is technical writer for WindowsCentral.com. His primary focus is to write comprehensive how-tos to help users get the most out of Windows 10 and its many related technologies. He has an IT background with professional certifications from Microsoft, Cisco, and CompTIA, and he's a recognized member of the Microsoft MVP community.

30 Comments
  • What a coincidence.
    Was just clean installing (Windows 10) days ago and faced a problem that was preventing the installation.
    The problem was that the disk was MBR and Windows needed it to be GPT.
    Eventually I backed up all my data and formatted the whole disk.
  • <p>Why you hadn&#39;t try mini tool Partition Manger to convert MBR to GPT</p>
  • There was a weird problem that prevented Windows from booting even in safe mode.
    Command prompt wasn't working as well.
    It was a very weird problem.
  • Cool, very useful. Too bad I'm still using old hardware which doesn't even support UEFI, but It'll come in useful ine day.
  • In that case, not really. With modern hardware, UEFI is default 🙂
  • Not quite. My friend built a new PC a few months back and he's still on standard old BIOS.
  •  This guide should  come with a warning. I changed my boot drive from a HDD to a SSD a few years back and made the move to GPT.   I have been unable to install major updates via Windows Update or via the media creation tool ever since. For whatever reason Windows tries to install to a non-existing MBR partition and hangs on the install. The only way I've been able to install the updates is by using a 3rd party tool to create a GPT formatted USB boot device. This then means I cant update the OS I have to do a clean install from the USB pen.  
  • Man, and I thought the Air Force was good at acronym vomit -- best headline ever!
  • Funny, I didn't even realise it.  I guess I'm nerd enough to know what all those acronyms are!
  • When I try to use the mbr2gpt /allowFullOS command, it says "invalid arguments" and lists all the arguments which can be used with the tool. I even tried copy/pasting the command from this webpage and even the list of arguments but still fails. Also tried using CMD in both normal and administrator modes. What could be the issue? :/ Running Windows 10 Pro version 1703.
  • You can it working if you use it like this: mbr2gpt /validate /allowfullos, you need to append the /allowfullos after each command you would use during the process. Thanks,
  • I see. Thank you very much.
  • Wow, I need a tutorial just for reading the article's title!
  • This is a very good article, it will be useful to many people, thank you.
  • Wow, I never made the connection between UEFI and GPT.  I wondered why I couldn't get my computer to boot using UEFI.  So, I followed your steps and got it working!  (I even did the GPT conversion on the running OS; brave, I know.)  It's a Dell Precision T3600.
  • Thanks for this very useful article.
  • So, I have a couple of questions. Forgive me if they're stupid ones. My computer has two SSDs, a C and D drive. I keep the operating system and programs on the C drive and use D everything else. Will this process convert both those drives at once? And I'm kind of wondering about my backup drive. Seems logical to disconnect it before doing all this, but then when I hook it back up to serve as my backup drive again, will it work with the converted drives? And how do I get out of the Windows PE environment after converting the drive? Thanks.
  • So, I have a couple of questions. Forgive me if they're stupid ones. My computer has two SSDs, a C and D drive. I keep the operating system and programs on the C drive and use D for everything else. Will this process convert both those drives at once? And I'm kind of wondering about my backup drive. Seems logical to disconnect it before doing all this, but then when I hook it back up to serve as my backup drive again, will it work with the converted drives? And how do I get out of the Windows PE environment after converting the drive? Thanks.
  • You need to the available options mbr2gpt /? to select the disk. According to Microsoft, this isn't a non-destructive process, but it's not a bad idea to disconnect the drives, the only drive that matters is the boot drive to start Windows again. To exit Windows PE, click the X red button on the top-right. Use the Shutdown /t 00 /r command. Or restart your computer. Thanks,
  • can we revert this process???
  • Thank you for the very informative and helpful tutorial 👍
  • Under the (MBR2GPT important details) section, there's a small typo.
    It should be version 1703 istead of 1793.
  • *delete* Nevermind, was clicking the wrong thing.
  • Hey Mauro, Under the section "How to convert a drive from MBR to GPT on Windows 10" Step 4 is incorrect. At least on Windows 10 version 1903. To get to where you expect to be in step 4, you need to switch the tab to "hardware", and then press the button "properties" - THEN you see the volumes tab - in the new window. However, in step 5's screnshot, the fields are already filled. That's also not the case. On my device, you have to press the "Fill out" button next to the grayed out "properties" button. I haven't checked what else is different from your article. But thought I would mention it 🐱‍👤
  • Really timely article as I needed to do this on a company PC. A couple of things to note: 1) If you have Hyper-V installed, uninstall the "Hyper-V Platform" in Windows Features before doing this and re-install after as the UEFI BIOS change breaks that and a reinstall fixes it. (You can uninstall/reinstall after just following the steps too) 2) Bitlocker also appears to get 'broken' by the BIOS change (legacy to secured). We suspended Bitlocker before doing the conversion with the expectation that it could just be re-enabled afterwards but that didn't work. So we're currently turning it off (decrypting) with the expectation it can be cleanly re-enabled afterwards. 3) Strongly recommend that users also check for a BIOS upgrade as the Dell XPS15 we upgraded had quite an old BIOS that didn't support all the UEFI PCR7 features. Upgrade to get SecureBoot fully working with Windows 10.
  • Curious your comment ...
    "Finally, while drives using the MBR style can have up to four primary partitions, the drive that you want to convert can't have more than three partitions, because one additional allocation is required to create the UEFI system partition. “ This system now upgraded to W10 1909 has “4 partitions” but on 3 are primary, one is recovery.
    I am curious on the disclaimer if you mean “max 3 primary” or “max 3 of any kind of partitions”?
    I have 4, 3 primary, 1 recovery.
  • This article should be republished. I had to convert my C drive to GPT to enable UEFI and Secure Boot so that my PC can update to Windows 11.
  • Have you disabled CSM?
  • I did this to enable Windows 11 compatibility and it's really simple if you follow the steps.
  • My pc now ask me reboot or select proper boot device when I turn it on! Help please!!!