MBR2GPT: Convert MBR to GPT

If you’re looking to upgrade your Windows PC, install a modern operating system, or enable features like Secure Boot, you may have run into the terms MBR and GPT. These are partition styles used by your hard drive. Many newer features require GPT. Fortunately, Microsoft provides a built-in tool called MBR2GPT to convert disks from MBR (Master Boot Record) to GPT (GUID Partition Table)—often with zero data loss.

What’s the Difference?

MBR (Master Boot Record):
- The older partition style.
- Supports up to 2TB drives and four primary partitions.
- Used by legacy BIOS systems.
GPT (GUID Partition Table):
- The modern standard.
- Supports drives larger than 2TB.
- Allows unlimited partitions (Windows supports up to 128).
- Required for UEFI boot mode and Secure Boot.

Why Convert MBR to GPT?

To install or upgrade to Windows 11.
To use UEFI boot (faster, more secure).
To use disks larger than 2TB.

Meet MBR2GPT

MBR2GPT.exe is a command-line tool included in Windows 10 and later. It safely converts an MBR disk to GPT format without erasing your data.

Key Benefits:

No data loss (if used correctly).
Built-in—no need for third-party software.
Fast and efficient.

How to Use MBR2GPT

Warning: Always back up your data before making partition changes. While MBR2GPT is reliable, things can go wrong.

Step 1: Check Your Disk

Open Command Prompt as an administrator and run:

diskpart
list disk
exit

Look for your disk. If it shows an asterisk (*) under “GPT,” it’s already using GPT.

Step 2: Validate the Disk

MBR2GPT can only convert system disks (the disk with Windows installed) and only from a Windows PE (Preinstallation Environment) or recovery environment.

Boot into Windows PE or Advanced Startup, open Command Prompt, and run:

mbr2gpt /validate /disk:0 /allowFullOS

Replace 0 with your disk number if it’s different.
/allowFullOS lets you run this in full Windows (only if needed).

If validation passes, you’re ready.

Step 3: Convert

Run:

mbr2gpt /convert /disk:0 /allowFullOS

The tool will shrink one partition if needed to make room for UEFI system partitions.
Wait for the process to complete.

Step 4: Change Firmware Settings

After conversion, you must change your BIOS settings from Legacy BIOS to UEFI mode for the system to boot.

Restart your PC.
Enter your BIOS/UEFI settings (usually by pressing F2, DEL, or ESC on startup).
Switch boot mode to UEFI.
Save and exit.

That’s It

Your system is now running GPT. You’re ready for Secure Boot, modern Windows versions, and larger drives.

Common Issues & Tips

Back up your data first.
MBR2GPT only works on system disks (with Windows installed).
If you dual boot or have older OSes, check their compatibility.
If you run into boot issues, try running Windows Startup Repair or revert firmware to Legacy mode.

Final Thoughts

MBR2GPT makes it simple to modernize your hard drive without wiping your system. Take a backup, follow the steps, and enjoy the benefits of GPT. If you have questions or run into issues, drop a comment below!

Mark Vincent

Tech enthusiast and content creator passionate about making technology simple for everyone. I share practical tips, guides, and reviews on the latest in computers, software, and gadgets. Let’s explore the digital world together!