Can I change MBR to GPT?

Yes, it is possible to convert a disk from MBR (Master Boot Record) to GPT (GUID Partition Table). This conversion can offer significant advantages, particularly for modern systems and large storage devices.

Why Convert MBR to GPT?

Converting to GPT provides several benefits over the older MBR partitioning scheme, aligning with the capabilities of modern hardware and operating systems.

Advantages of GPT

Supports Larger Disks: GPT can handle disks larger than 2 terabytes (TB), while MBR is limited to 2 TB.
More Partitions: GPT allows for virtually unlimited primary partitions, whereas MBR is restricted to four primary partitions (or three primary and one extended partition containing logical drives). Windows typically supports up to 128 GPT partitions.
Improved Data Integrity: GPT stores multiple copies of the partitioning table across the disk and includes Cyclic Redundancy Check (CRC) values to detect and correct errors in the partition table, enhancing data reliability.
Required for UEFI: GPT is a prerequisite for systems that utilize UEFI (Unified Extensible Firmware Interface) firmware for booting, which is standard on most modern computers. UEFI offers faster boot times and enhanced security features compared to the legacy BIOS.

MBR vs. GPT Comparison

Feature	Master Boot Record (MBR)	GUID Partition Table (GPT)
Max Disk Size	2 TB	9.4 ZB (Zettabytes) - practically unlimited
Max Partitions	4 Primary, or 3 Primary + 1 Extended (with Logical)	128 (Windows default), practically unlimited
Boot Mode	BIOS (Legacy)	UEFI
Data Redundancy	Single partition table location	Multiple copies of partition table, CRC protection
OS Support	All Windows versions	Windows 7 64-bit and later (for boot drives)

How to Convert MBR to GPT

The primary method for converting a disk from MBR to GPT typically involves using the Diskpart utility in Windows. It's crucial to understand that this method will erase all data on the disk, so a complete backup is essential before proceeding.

Method 1: Using Diskpart (Data Loss Involved)

This is the most common and robust method, particularly effective for converting system or data drives. However, it requires wiping the disk clean before conversion.

Prerequisites:

Backup All Data: Seriously, back up everything from the target disk.
Windows Installation Media: If converting your operating system drive, you'll need Windows installation media (USB or DVD) to boot from and access the Command Prompt, or to reinstall Windows after conversion.

Steps to Convert using Diskpart:

Open Command Prompt as Administrator:
- If converting a data drive on a running system: Search for "cmd", right-click "Command Prompt", and select "Run as administrator".
- If converting an OS drive: Boot your computer from Windows installation media, select your language, then choose "Repair your computer" > "Troubleshoot" > "Command Prompt".
Launch Diskpart:
- Type diskpart and press Enter.
Identify the Target Disk:
- Type list disk and press Enter. This will display a list of all disks connected to your computer. Carefully identify the disk you want to convert by its size and number.
Select the Disk:
- Type select disk # (substitute # with the actual disk number, e.g., select disk 1) and press Enter. Ensure you select the correct disk, as the next step is destructive.
Clean the Disk:
- Type clean and press Enter. This command will delete all partitions and data on the selected disk.
Convert to GPT:
- Type convert gpt and press Enter. This command converts the disk to the GPT partitioning scheme.
Exit Diskpart:
- Type exit and press Enter.
Create New Partitions (Post-Conversion):
- After conversion, the disk will be unallocated. You'll need to create new partitions and format them to store data. You can do this using Windows Disk Management or by continuing in Diskpart. If it was your OS drive, you can now proceed with installing Windows in UEFI mode.

For a visual guide on using Diskpart, you can refer to Microsoft's official documentation on Diskpart Command-Line Reference.

Method 2: Using Windows Disk Management (For Empty Disks)

If your disk is completely empty (unallocated) and not initialized, Windows Disk Management offers a graphical way to convert it.

Open Disk Management: Right-click the Start button and select "Disk Management."
Locate the Disk: Find the disk you want to convert. It must show as "Unallocated."
Convert to GPT: Right-click on the disk number (not a partition) and select "Convert to GPT Disk." If this option is grayed out, it means the disk is not unallocated, or it contains partitions.

Method 3: Third-Party Tools (Without Data Loss)

Some third-party partition management software offers the ability to convert MBR to GPT without losing data. These tools typically involve a more complex process and may not be free. Always research and choose reputable software, and still back up your data as a precaution.

Important Considerations Before Conversion

Data Backup is Paramount: Reiterating this, never attempt a conversion without a full backup, especially when using methods that wipe the disk.
UEFI Firmware: If you're converting your primary OS drive, your computer's motherboard must support and be configured to boot in UEFI mode. Check your BIOS/UEFI settings for this.
Operating System Compatibility:
- Modern 64-bit Windows versions (Windows 7, 8, 10, 11) can boot from GPT disks.
- 32-bit Windows versions can only use GPT for data disks, not for booting.
- Older operating systems may not support GPT at all.
Reinstallation Required for OS Drives: If you convert an MBR OS drive using the clean command, you will need to reinstall your operating system afterward, ensuring it's installed in UEFI mode to boot from the new GPT disk.

Converting from MBR to GPT is a straightforward process once you understand the implications, particularly the need for data backup and the relationship with UEFI booting.