How to Convert GPT to MBR (or MBR to GPT) without Operating System?

February 1, 2019

If you have met the MBR GPT problem while installing Windows OS, then, you can find a way to convert GPT to MBR (or MBR to GPT) without operating system. Here provides you two methods for how to convert GPT to MBR without data loss having no access to OS.

Scenario

“I have a computer installed with Windows 8 operating system. I was planning to operate it with Windows 7. But while installing Windows 7, when I formatted the partition and tried to install it, it shows the partition is in GPT format. I guess it means I need to convert GPT to MBR. However, how to convert GPT to MBR without operating system?”

Actually, there are many reasons that lead users to want to convert GPT disk to MBR disk or convert MBR to GPT disk. For example, the Windows 32 bit operating system can only boot from MBR disk, thus, you may need to convert GPT to MBR before install a Windows 32 bit operating system. Generally, it is not a complex thing of converting data disk between MBR and GPT disk in Windows OS. However, if you need to convert GPT to MBR without operating system like the Scenario, it would be a little bit troublesome.

How to convert GPT to MBR during Windows installation?

To convert GPT to MBR without operating system, you could finish the task during Windows installation.

1. plug in a Windows installation CD/DVD, and start to install Windows, meanwhile, press Shift + F10 to open command prompt window.

2. Type Diskpart in the cmd.

3. Type list disk. Mark the disk number you want to convert to MBR.

4. Type select disk n (n refers to the disk number of the disk you need to convert).

5. Type clean. It will delete all partitions and data on the disk. Make sure there is no important data or back it up before doing that.

6. Type convert mbr. It will convert the selected drive into MBR.

How to convert GPT to MBR without data loss having no access to OS?

While using Diskpart to convert GPT to MBR without operating system would also be losing data. Besides, the operations on command prompt are irrevocable which may cause a big damage during operating. Well, how to safely convert GPT to MBR without data loss having no access to OS?

AOMEI Partition Assistant software

AOMEI Partition Assistant software is a perfect disk manager for Windows operating system. It can help you manage your hard drive better, such as resize partition, format partition, wipe hard drive, etc. What the important is, you can use it to safely convert GPT to MBR without operating system and without losing data.

Detailed steps of how to convert GPT to MBR without operating system

Step1. First, you need to create a bootable media (a CD/DVD, USB drive is also OK). Here we create a bootable USB drive with AOMEI Partition Assistant. You may be required to install Windows ADK or Windows AIK (Download Windows ADK). If you have installed Windows AIK/ADK in your system, you need to find the WIM file under the installed directory of AIK or ADK, and manually set the file path into the following box.

1>. Connect a 16GB or larger USB flash drive to a working Windows computer.

2>. Install and launch AOMEI Partition Assistant. Select Make Bootable Media on the main interface. It will bring you into Create Bootable Media Wizard.

Make Bootable Media

3>. Select USB Boot Device and choose your USB as the target place to store the ISO file, click Proceed.

Choose USB Drive

4>. Wait till the progress done. Click Finish.

Finish

After creating a bootable media with AOMEI Partition Assistant, you can use it to convert GPT to MBR in BIOS.

Step2. Then you can start to convert GPT to MBR without losing data having no access to OS.

1>. Using the bootable USB to boot your computer by entering BIOS. getting into the main interface of AOMEI Partition Assistant.

Boot Preference

2>. To convert GPT to MBR without losing data, here you can right click the hard drive, select Convert to MBR Disk in the pop-up menu.

Convert Data Disk to MBR

3>. Then, you need to confirm the operation of converting GPT to MBR. Click OK.

OK to GPT Data Disk

4>. After that, you will back to the main interface, click Apply at the toolbar.

Apply to GPT Data Disk

This is how to convert GPT to MBR without operating system by using AOMEI Partition Assistant. If you need to convert MBR to GPT, you only need to right click the MBR disk, select Convert to GPT Disk in the pop up menu, and follow the wizard to convert MBR to GPT disk without data loss.

Note:

  • If there are more than 4 primary partitions on the GPT hard drive, AOMEI Partition Assistant will change the fourth partition and later partitions to logical partition automatically while converting.

  • AOMEI Partition Assistant allows you to convert boot disk between MBR and GPT. Convert boot MBR to GPT disk may unable to boot after the conversion because Windows 32 bit OS can only boot from MBR disk. Plus, you need to confirm that your motherboard supports EFI/UEFI.