How to change or convert mbr to gpt without data loss?

The MBR2GPT.exe tool will delete the whole partition and won't keep you data. Please use a dedicated disk partition tool for changing or converting MBR to GPT.

Converting a disk from Master Boot Record (MBR) to GUID Partition Table (GPT) without data loss is a common necessity, especially for upgrading to newer operating systems like Windows 11 or utilizing large drives (over 2TB).

Regardless of the MBR to GPT conversion method used, always back up all critical data before attempting any disk partition style conversion. While MBR2GPT and certain third-party tools are designed to be non-destructive, any operation involving the partition table carries a small risk of data loss.

For Windows system disk conversion, the official Microsoft tool, MBR2GPT.exe, is the safest and most standard choice, provided your disk layout meets the requirements (e.g., no logical partitions and running Windows 10 version 1703 or later).

MBR2GPT.exe Limitations (Cons)

System Disk Only: The tool is designed exclusively to convert the system (OS) disk that holds the operating system. It cannot be used to convert data-only disks from MBR to GPT.

Maximum 3 Primary Partitions: The MBR disk to be converted must have 3 or fewer primary partitions.

No Extended/Logical Partitions: The disk must not contain any Extended or Logical partitions. The tool is incompatible with this MBR partitioning scheme.

Requires BIOS to UEFI Conversion: The MBR2GPT tool only converts the partition style on the disk. For the computer to boot, you must manually change the firmware (BIOS) settings from Legacy/CSM to UEFI Mode after the conversion is complete. Failure to do this will result in a non-bootable system.

Using Windows Setup to change MBR to GPT involves booting your computer from a Windows installation media (like a USB or DVD) and using the tools available during the installation process to erase and reformat the disk. Essentially, this method is suitable when you're installing or reinstalling Windows, and it allows you to change the disk to GPT as part of the setup process.

Here's a simplified overview of how it works:

1. Prepare and boot from Windows installation media: You insert a bootable Windows USB or DVD and restart your computer. You might need to change the boot order in your BIOS/UEFI settings so that the computer boots from the installation media.
2. Start Windows installation process: Once booted, follow the prompts to start installing Windows. When asked where to install Windows, you'll see your drives and partitions.
3. Access Command Prompt: At this point, you press Shift + F10 to open a Command Prompt window. This allows you to run disk management commands directly.
4. Use disk partitioning tools: In Command Prompt, you run the diskpart utility. You list available disks, select the one you want to convert, then delete all existing partitions with the clean command. This effectively erases everything on the disk.
5. Change MBR to GPT: After cleaning the disk, you run the convert gpt command within diskpart. This changes the disk's partition style from MBR to GPT.
6. Proceed with Windows installation: Once the disk is converted, you close the Command Prompt and continue installing Windows on the unallocated space. Your system now uses a GPT disk, and if your BIOS/UEFI settings support it, Windows will install in UEFI mode.

Please use a dedicated partition manager and make a bootable media.

While many partition managers exist, using their bootable media (a disc or USB) to perform the conversion outside of the running Windows operating system can be considered an "unusual" approach compared to simply running the software in Windows or using MBR2GPT.exe.

Convert mbr to gpt without data loss

Step 1: Create a bootable media (USB or CD) using the third-party software.

Step 2: Boot your computer from this media.

Step 3: Run the MBR-to-GPT conversion function within the software's dedicated environment.

Step 4: Reboot and ensure your firmware is set to UEFI mode.

Most users prefer to use the Windows-native MBR to GPT converter (MBR2GPT.exe) for the OS disk, or the desktop application of a partition manager for a non-OS disk. Booting into a specialized pre-installation environment to perform the task is less common, but it can be necessary if the Windows OS is unstable or the standard tools fail.

Using a Linux Live environment with tools like parted or gdisk is a viable and relatively free method to convert MBR to GPT on a Windows computer. This approach is often preferred by advanced users because it provides more control and can be performed without installing any software on Windows itself.

 Here's what you need to know:

1. Create a Linux Live USB/CD

   Download a Linux distribution like Ubuntu or Linux Mint.

   Create a bootable USB drive or DVD using tools like Rufus or BaleneE-tcher.

2. Boot into Linux Live Environment

   Restart your computer.

   Boot from the USB/DVD (you may need to change boot order in BIOS/UEFI).

   Select "Try Linux" mode (so you don’t install anything).

3. Identify the Disk

   Open a terminal window.

   Run lsblk or fdisk -l to list disks and identify your target disk (e.g., /dev/sda).

Using gdisk to Convert MBR to GPT

gdisk is a powerful, command-line utility for partitioning disks, especially for converting MBR to GPT:

Steps:

1.Launch gdisk:

sudo gdisk /dev/sdX

   Replace /dev/sdX with your disk (e.g., /dev/sda).

2.Check the disk:

  Type b to back up the current partition table (optional but recommended).

  Type p to print the current partition table and review it.

3.Convert to GPT:

  If the disk is MBR, gdisk will detect it.

  You can convert MBR to GPT.

4.Write changes:

  Type w to write the new partition table to disk.

  Confirm when prompted.

You can convert MBR to GPT using the built-in Disk Management tool. 

This is a destructive conversion method that requires complete data erasure. It's suitable when:

• You're setting up a new disk
• You have complete backups of all data
• You're planning a clean Windows installation
• You don't need to preserve the existing OS installation

How to convert mbr to gpt with data loss

1. Copy all files, programs, and system data to an external drive or cloud storage Verify your backup is complete and accessible.

2. Ensure your motherboard supports UEFI firmware (most computers since 2012 do)

3. Press Win + R → Type diskmgmt.msc → Enter.

4. Right-click on the disk label (left side where it says "Disk 0," "Disk 1," etc.) 

5. Select "Convert to GPT Disk".

Choose This Method When:
✅ You're installing a fresh copy of Windows
✅ You have complete, verified backups
✅ You want the cleanest possible GPT setup
✅ The mbr2gpt tool fails or isn't available

Choose Another Method When:
❌ You need to preserve existing Windows installation (use mbr2gpt.exe)
❌ You can't backup data (use third-party tools with data preservation)
❌ You're not technical (use Windows Setup automatic conversion)

Manual partition cloning is an advanced, risky, and complex method to convert MBR to GPT without data loss. It involves creating a new GPT disk, copying all partitions from the old disk, and adjusting the boot configuration accordingly. Here's an overview of how it works and what it involves:

Steps of converting MBR to GPT:

1. Create a new GPT disk:
    Use a tool like Disk Management or third-party tools to initialize a new disk as GPT.
2. Clone all partitions:
   Use free cloning software to clone each partition from the MBR disk to the GPT disk.
   Ensure the cloned partitions are identical and in the same order.
3. Repair or recreate the bootloader:
   Since Windows boot records are different between BIOS/MBR and UEFI/GPT, you'll need to:
   Boot into a Windows recovery environment.
   Use tools like bootrec and bcdboot to fix the EFI bootloader.
4. Switch BIOS to UEFI mode:
   Enter your BIOS/UEFI settings and change the boot mode from Legacy BIOS to UEFI.
5. Test booting Windows:
   Boot from the new GPT disk and verify everything works.

While technically feasible, manual partition cloning is complex and risky for most users. It’s mainly used by advanced users or IT professionals.

If you are looking for a free methods to change MBR to GPT without data loss, your options are quite limited, as most reliable tools are either mainstream or involve risks. However, here are some less common approaches that might work, but please proceed with caution and backup your data first:

Some open-source tools or scripts are less known but can help convert disks:

Such as GPT fdisk (gdisk):

This is a command-line utility available for Windows that can change MBR to GPT.

How to use:  

1. Download GPT fdisk from github's website.
2. Run gdisk on your disk. It has an option to convert MBR to GPT.
3. During the process, select the "Convert MBR to GPT" option.
4. It can preserve data if used carefully, but manual partition editing is risky.
5. Important: Read the documentation thoroughly before proceeding.

Converting MBR to GPT without data loss is possible using specialized tools designed for this purpose. Here are your options:

Use MBR2GPT Tool (Built-in Windows Utility)
Windows 10 and Windows 11 include the MBR2GPT utility, which can convert MBR to GPT without data loss.

Important: Your system must meet certain requirements:

• The disk should have no more than 3 partitions (excluding the EFI system partition and recovery partitions).
• You should have a UEFI firmware (not BIOS).
• The disk should be healthy and free of errors.

Steps to use MBR2GPT:
1. Backup your data: Always recommended before making disk modifications.
2. Open Command Prompt as Administrator.
3. Run the validation command:

mbr2gpt /validate /disk:<disknumber> /allowFullOS

Replace <disknumber> with your disk number (you can find it in Disk Management).

4. If validation passes, proceed with conversion:

mbr2gpt /convert /disk:<disknumber> /allowFullOS

5. After you convert MBR to GPT, you need to change your firmware settings from Legacy BIOS to UEFI in the BIOS/UEFI firmware settings.