How to Convert MBR to GPT Without Losing Data

If you are upgrading from an older Windows version to Windows 11, you'll get a message that the disk is currently using MBR and must be GPT. The same message may appear in other scenarios as well, where you'll be asked to replace MBR with GPT. You can convert MBR to GPT through different methods, but if done incorrectly, it can wipe out your data. In this guide, we'll learn how to do this conversion while keeping the data safe. We'll check out both Windows' built-in tool and 3rd-party solutions. So, let's get started and learn to safely convert MBR to GPT without any risk of data loss. Here we go!

What Is MBR and Why Does It Still Exist?

To begin with, MBR stands for Master Boot Record. It’s an old partitioning scheme that was introduced way back in 1983. It's the same year that IBM released the PC XT. At that time, MBR was a good and reliable solution. But with the passage of time, both hardware and software have changed considerably.

MBR stores all the partition information in the first sector of a disk. To be precise, the MBR record consumes the first 512 bytes of this sector. It does work, but it has limitations:

Maximum 2 TB disk size: If you are using MBR on a disk larger than 2 TB, the remaining space will be inaccessible and will be of no use.
Maximum 4 primary partitions: Although there are workarounds to bypass this limitation, it is cumbersome.
No redundancy support: MBR corruption means you are going to lose your data, as there is no backup MBR record for recovery.
BIOS-only boot: It only works with older BIOS and doesn't support the new UEFI standard.

Still, there are millions of older devices that are running Windows 7 or 8 that have MBR as their partitioning scheme.

What Is GPT and Why Is It Better?

GPT stands for GUID Partition Table. MBR can be replaced with this modern partitioning scheme that was developed adhering to the UEFI specification.

The following features make it way better than MBR:

Maximum 9.4 ZB (zettabytes) disk size: That's enough to last a lifetime.
Maximum 128 primary partitions: You can imagine how many boot options you have to try out every operating system.
Multiple backup copies: It stores multiple copies of partition data at different locations on the disk.
CRC32 checksums: It's used to verify whether the partitioning data is corrupted or intact.
Prerequisite for UEFI Secure Boot: All modern operating systems boot through UEFI and thus need GPT.

It's a modern, flexible, secure, and powerful alternative to MBR.

MBR vs GPT: A Quick Comparison

Feature	MBR	GPT
Maximum Disk Size	2 TB	9.4 ZB
Primary Partitions	4	128 (Windows)
Firmware Compatibility	BIOS	UEFI
Data Redundancy	None	Yes (backup header)
Integrity Checking	None	CRC32 Checksums
Windows 11 Support	No	Yes
Secure Boot	No	Yes
Recovery Options	Limited	Better

When Should You Convert MBR to GPT?

If one of the following things applies in your case, it's time to switch to GPT:

The setup wizard is blocking the installation during the new Windows 11 installation process.
You have a disk of size larger than 2 TB.
You are looking to enable UEFI Secure Boot on your system.
You want to upgrade to a modern UEFI motherboard.
Due to a corrupted MBR, your system is unable to boot.
You've just purchased a new SSD, and you want it to be future-compatible right from the beginning.

Before You Convert: Things You Absolutely Must Do

No matter how technically sound you are, partition table conversion is a delicate task and cannot be taken lightly. The following are some of the preparations you must do before starting the conversion process.

1. Back Up Your Data

This is mandatory. Although the methods given below are safe, other things can go wrong. For example, a power failure during the key conversion step or a hardware failure. Make sure to back up your important files both to a secondary disk and to a cloud storage account.

2. Check Your Current Partition Style

Before moving ahead, first confirm which partition style your disk is currently using.

Press the Win + X key combo and select Disk Management from the context menu.
Right-click on the disk (left side). For example, Disk 0 or Disk 1.
Go to the Properties > Volumes tab.

📷 Partition table type information
Check the Partition Style field. You will either see MBR or GPT here.

If you prefer command-line, open the command prompt and run the following two commands:

diskpart
list disk

📷 Detect partition table type through the diskpart tool

Pay attention to the Gpt column. If an asterisk (*) is present, it's GPT. And if not, it's MBR.

3. Check If Your Motherboard Supports UEFI

If you are using GPT, UEFI firmware is a must. Although computers made after 2012 support it, there's no harm in confirming it explicitly.

Press the Win + R key combo. Type msinfo32 and hit the Enter key.
On the system summary page, pay attention to the BIOS Mode field.
If it says UEFI, you have to do nothing. If it says Legacy, you have to change the mode in your system's firmware settings.

4. Plug In Your Laptop

Do not run your laptop on battery; plug it into a power source. This is a critical process, so ensure a power backup is in place too.

Method 1: Using MBR2GPT (Built-in Windows Tool)

This powerful tool was introduced in Windows 10 (version 1703). It safely converts the OS drive from MBR to GPT. There's no data loss. It's the best and most preferred option for most users.

Requirements for MBR2GPT

OS must be Windows 10 version 1703 or later. Or Windows 11.
The number of primary partitions should be 3 or fewer.
No dynamic volumes should be present on the disk.
UEFI boot support should be present on the system.

Step-by-Step: Converting with MBR2GPT

Open a command prompt window as an administrator.
Now validate to check if your disk qualifies. You must replace 0 with your disk number if required.
```
mbr2gpt /validate /disk:0 /allowFullOS
```
If validation is successful, you’ll see a message like this:
```
MBR2GPT: Validation completed successfully
```
If an error occurs, the reason will be explained. For example, too many partitions or an unsupported disk layout.
Now start the conversion process.
```
mbr2gpt /convert /disk:0 /allowFullOS
```

The conversion process may take about half a minute, and you'll see messages like these while the conversion is going on.

MBR2GPT: Attempting to convert disk 0
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
MBR2GPT: Trying to shrink the OS partition
MBR2GPT: Creating the EFI system partition
MBR2GPT: Installing BOOTMGR into EFI system partition
MBR2GPT: Updating BCD settings
MBR2GPT: MBR partition cleanup
MBR2GPT: Conversion completed successfully

Now is the right time to switch your system's firmware to UEFI Mode. To do that, follow these steps:
- Reboot your PC and enter the firmware setup interface by pressing the Del, F2, F10, or Esc key. Refer to your motherboard manual to see which key you need to press.
- Look for the boot settings where you'll find options like Boot Mode, CSM, or Legacy Support.
- Change it to UEFI or UEFI Only. Make sure you also disable CSM (Compatibility Support Module).
- Finally, save the changes and exit from the firmware settings.

From here on, Windows will always boot in UEFI mode with the GPT partition table.

Method 2: Using Disk Management or DiskPart (For Non-OS Data Drives)

If you are looking to convert a non-Windows secondary drive, the process is straightforward. But it involves partition deletion.

If data on this secondary drive is not important, here's how to do it:

diskpart
list disk
select disk 1        (replace 1 with your disk number)
clean
convert gpt

Note: The clean command will wipe out all the data on the disk.

If you want to preserve the data, use the method given below.

Method 3: Using AOMEI Partition Assistant

If the Windows built-in tool is not working for you or you are worried about data loss, a 3rd-party app can do all the heavy lifting while keeping your files and folders intact.

AOMEI Partition Assistant is one of the best tools for this conversion process. Its free version can do the MBR to GPT conversion without any data loss.

Step-by-Step: Converting with AOMEI Partition Assistant

Download the application from the official AOMEI website. Its free edition is good enough for MBR to GPT conversion.
Open the application and right-click on the disk you want to convert to GPT.

📷 Converting disk from MBR to GPT
Select the Convert to GPT option from the context menu.

📷 Confirm disk selection
A dialog box will appear. Click the OK button.
Now click the Apply button in the top-left toolbar. To confirm, click the Proceed button.
Wait till the process is complete. Typically, it takes less than a minute.

Method 4: Converting Inside Windows Setup (During OS Installation)

For a new Windows 10 or 11 installation, you can ensure that the disk is using GPT right from the beginning. You can configure it during the installation process.

Start by booting from the Windows USB installer.
When the message appears: "Where do you want to install Windows?", press the Shift + F10 key to open the command prompt window.

Now run the following commands in the given order:

diskpart
list disk
select disk 0
clean
convert gpt
exit

Close the command prompt window and refresh the partition list. You can now continue with the rest of the installation process.

Remember, this method will erase all the data from the disk. So, make sure you are using it only for a clean installation.

Verifying the Conversion Was Successful

Verification is as important as the conversion process itself. Here's how you can verify it:

Using Disk Management:

Press the Win + X key combo and select Disk Management from the context menu.
Right-click on the disk (left side). For example, Disk 0 or Disk 1.
Go to the Properties > Volumes tab.
Check the Partition Style field. You should now see GPT here.

Using DiskPart:

Open the command prompt window with admin privileges and execute the following commands:

diskpart
list disk

If asterisk (*) is present in the Gpt column, you are good to go.

Using PowerShell:

Get-Disk | Select-Object Number, PartitionStyle, Size

Conclusion

MBR to GPT conversion used to require a complete wipe of your drive and a complete reinstall from scratch. Not so anymore, in most cases. By using Microsoft's own MBR2GPT tool built into every Windows 10/11 installation, you can convert MBR to GPT without losing a single file in less than 60 seconds. With AOMEI Partition Assistant, you can do it the easy way.

Some Key Points to Note:

Back up before you start (always!)
Use MBR2GPT if the operating system is Windows 10/11, and there are 3 or fewer primary partitions on your disk.
Use AOMEI or a similar tool when you do not want to lose data while working on a secondary drive.
Reboot into your firmware settings and switch to UEFI mode. If you do not do that, you won't be able to boot from your disk.
Don't say that you're done until you verify the conversion was a success.

If you are not confident about the process, seek the help of an expert instead of doing it yourself.