How to Convert GPT to MBR Without Operating System

Updated By

Tracy King 

Written By

Linda 

Last Updated on April 22, 2024

This page offers two direct solutions to convert GPT to MBR without Windows OS. If you're installing a Windows system, like Windows 10/8/7, but encounter an error message "The selected disk is of the GPT partition style...", stay calm and fix the issue yourself with either of the following methods:

# 1. Convert GPT to MBR without an OS using a bootable USB tool

# 2. Convert GPT to MBR without OS using CMD

How to convert GPT to MBR without operating system with utf-8 encoding?

"I wiped Windows 7 from my system with the intention of installing Windows 10. But when I tried to install Windows 10, it told me 'Selected disk is of GPT partition style' and refused to format the partition."

"How can I convert GPT to MBR without an operating system and without losing data?"

Some users can't install Windows on GPT due to their computer not supporting UEFI boot.

For example, a 32-bit version of Windows can only boot from an MBR disk, so you would need to convert from GPT to MBR before installing the system. If your disk is formatted as GPT and your computer doesn't support UEFI/EFI mode booting, you will also need to convert it to MBR.

Normally, you could use the built-in Disk Management and Command Prompt to convert GPT disk to MBR. But if there is no Windows system installed on your computer, it's not an easy job to change partition style from GPT to MBR on the disk.

Don't worry. In the following content, we will show you two methods to convert GPT to MBR without OS. You can use a partition manager or the Diskpart command to do this.

Convert GPT to MBR without OS using a bootable USB with conversion tools:

With the help of professional partition manager – tools Partition Master, you can convert GPT to MBR without Windows OS in two steps.

First, create a bootable disk (on a USB drive or CD) on a healthy computer, and then connect the bootable USB drive to the target PC and start the computer from the bootable disk.

Secondly, you can use a disk management tool to convert GPT to MBR without OS access. No data will be lost in the process!

Please refer to the detailed steps:

Step 1: Connect a blank USB drive to your computer and launch Partition Master. Go to Bootable Media, select “Create Bootable Media,” and click “Next” to proceed.

Create Bootable Disk of Partition Master Tools

Step 2: Create a bootable disk for Partition Master.

Select the USB device and click "Create" to make the bootable tool on the USB drive.

Create a Bootable Disk Wizard

Step 3: Connect the bootable WinPE disk to the target computer and configure the system to boot from the USB tool media.

Restart your computer and press F2 or Del to enter BIOS. Set the boot order to boot from "Removable Device" (bootable USB drive) before the hard drive. Press "F10" to save and exit.

Step 4: When the computer boots into the “Partition Master” tool, go to “Disk Converter” and select “GPT to MBR”. Then click on “Next” to proceed.

Step 5. Select the target GPT disk that you want to convert to MBR, and click "Convert" to start the conversion.

In addition to disk conversion, the Partition Master tool also supports converting FAT to NTFS, and converting a logical partition to primary or primary to logical.

Converting GPT to MBR without an operating system using Command Prompt (CMD) might require some additional tools and steps, since CMD typically runs within an operating system environment. However, you can use an inbuilt Windows tool called "DiskPart," which can run from a Windows installation media. Here's the general process: 1. First, you'll need a Windows installation USB or DVD. Insert the installation media and boot your computer from it. 2. On the setup screen, choose your language and other preferences, then click "Next." 3. Click "Repair your computer" > "Troubleshoot" > "Advanced options" > "Command Prompt." 4. In Command Prompt, type the following commands to list all disks: ``` diskpart list disk ``` 5. Identify the number of the GPT disk you want to convert (usually 0 or 1), then enter this command to select the disk: ``` select disk X ``` Replace "X" with your disk number. 6. Wipe the disk data (this will delete everything, so be cautious!): ``` clean ``` 7. Create a new MBR-style disk: ``` convert mbr ``` 8. Finally, exit DiskPart and Command Prompt: ``` exit exit ``` 9. The computer will return to the setup screen. At this point, you can safely shut down, remove the installation media, and restart into your operating system (if you have one). Please note that this process will erase all data on the disk. Before proceeding, make sure you've backed up all important files. If unsure, it's best to seek professional assistance.

For those tech-savvy users who don't want to use a third-party disk partition manager, you can also convert GPT to MBR during Windows installation via CMD commands.

If you're reinstalling or installing Windows fresh and need to convert from GPT to MBR, follow these steps:

Step 1: Insert your Windows installation DVD/USB and start the Windows setup. While it's loading, press Shift + F10 to open a Command Prompt window.

Step 2. Type diskpart in the Command Prompt, and press Enter. Click Yes to open Diskpart.

Step 3. Type list disk, and press "Enter." Note the number of the disk that you want to convert to MBR.

Step 4. Type select disk 1 (replace 1 with the number of the disk you want to convert).

Step 5: Type clean and press "Enter". This will delete all partitions and data on the disk. Make sure you have backups!

Step 6: Type convert mbr and press "Enter". This will convert the empty GPT partition style to MBR.

You can then proceed to install Windows on the converted MBR disk, following the instructions on your computer screen.

Additional tip: Converting MBR to GPT without an OS

While this tutorial shows how to convert GPT to MBR without Windows using a WinPE boot disc and the built-in Diskpart command, there's also a significant need for converting from MBR to GPT without an operating system installed.

This is required when trying to create more than four primary partitions, fully utilize a disk larger than 2 TB, or install Windows on an EFI system. You can use the same method outlined here to do that.

A word of caution: using Diskpart to convert a disk will delete its partitions and data. To prevent data loss, back up your data beforehand or use tools like Partition Master to assist with the operation.

If you decide to use a disk partition manager utility, here are the detailed steps to convert MBR to GPT without reinstalling the OS:

Also, remember that you'll need a healthy computer to create the bootable USB drive if your system won't start up.

Step 1: Connect the empty USB drive or blank CD/DVD to a computer that is running properly. Launch AOMEI Partition Assistant and click "Make Bootable Media" then select "Create bootable media". Click "Next" to continue.

Create Bootable Disk Wizard

Step 2: Select USB or CD/DVD, then click "Create" to start creating your bootable media.

Step 3: Connect the USB drive with the boot media to your computer, and then restart your computer from the boot media tool.

Press F2 or Del to enter BIOS and set the computer to boot from "Removable Device" (boot USB drive) or "CD-ROM Drive" (boot CD/DVD). Press "F10" to save and exit, then restart your PC to access the tool boot media.

Step 4: After your computer boots into the Partition Master, choose “Disk Convert” and then click on “MBR to GPT”. Click on “Next” to proceed.

Step 5: Select the MBR disk that you wish to convert to GPT, and click "Convert" to start the conversion.

• If you chose to use the Diskpart CMD command during Windows setup, change the command from convert mbr to convert gpt after selecting the target disk.

1. What are GPT and MBR disks? GPT stands for GUID Partition Table, a modern disk partitioning format that supports more than 4 primary partitions and hard drives larger than 2TB. MBR (Master Boot Record) is the traditional boot record, which only supports up to 4 primary partitions or 3 primary partitions with 1 extended partition, with a maximum capacity of 2TB. 2. Why would you need to convert from GPT to MBR or MBR to GPT? - GPT to MBR: This might be necessary due to lack of support for GPT in older operating systems or hardware, or to install a system in BIOS mode. - MBR to GPT: Typically, this is because you need to utilize the space on a large hard drive greater than 2TB, or to install an operating system in UEFI mode for better boot performance and compatibility. 3. How can I tell if my disk is GPT or MBR? You can use disk management tools (like Windows' "Disk Management") or command-line utilities (such as diskpart) to view the disk's partition table type. 4. Will converting the disk format lose data? Yes, usually, all existing partitions and data will be deleted during the conversion, so it's crucial to back up important files beforehand. 5. How can I safely convert from GPT to MBR or MBR to GPT? Use professional disk management software like AOMEI Todo Backup, MiniTool Partition Wizard, etc., which offer data loss-free conversion options. Follow the steps provided by the software and ensure you back up your data before converting. 6. Do I need to reinstall the operating system after the conversion? Converting the disk format may require reinstalling the OS, especially when going from GPT to MBR, due to differences in UEFI and BIOS boot methods. Confirm your system's compatibility with the target partition table type before converting. 7. Can I perform the conversion while the system is running? Generally not; you'll need to do it in Safe Mode or on another computer. Some tools might offer in-place conversions, but these carry higher risks, so it's advisable to back up your data first. 8. What should I do if I encounter issues during the conversion? If problems arise during the process, check if you followed the correct steps and try using different tools or seek professional assistance. Always back up your data to prevent unexpected losses.

For those unfamiliar, you might still have questions about converting between GPT and MBR disks. We've gathered 5 questions asked by other users on Google Chrome and provided brief answers under each. Hopefully, these will also be helpful to you.

1. Can I convert GPT to MBR?

Yes, you can essentially change the partition style of a hard drive from GPT to MBR or vice versa. This means you can convert a disk on your computer to the desired partition style – either GPT or MBR.

How to convert MBR to GPT in Windows 10?

There are three ways you can change the disk partition style from MBR to GPT in Windows 10.

1. #1. Partition Master Tool
2. #2. Disk Management
3. #3. Use CMD Commands

You can use a tool like "Partition Master" to convert the disk from MBR to GPT without deleting any partitions or data. If you use either of the last two methods shown on this page, you can also convert the disk to GPT by deleting all partitions, thus erasing all your personal data. Make sure to back up your data beforehand in this case.

If you deleted the partition without backup, you can use the Partition Master software for lost partition recovery.

To convert the OS disk to GPT, first ensure that your computer supports UEFI boot in the BIOS. Then, use the Partition Master tool from a bootable USB converter as shown on this page to convert MBR to GPT.

3. Will I lose data when converting disk from GPT to MBR or from MBR to GPT?

If you use Disk Management or the Diskpart command line to convert a disk, the answer is yes. It will remove all partitions and data from the disk before changing its partition style.

If you use a third-party disk partition manager like Partition Master, no problem will occur. No data will be lost when converting between MBR and GPT disks.

4. How do I migrate my operating system from an MBR disk to a GPT SSD?

Basically, it's not feasible to migrate OS from MBR disk to GPT disk manually. Fortunately, with the help of tool Partition Master and its feature of Migrate OS to SSD/HDD, you can

How can I partition my hard drive without an operating system?

Normally, if the operating system fails to boot, the manual way of partitioning the hard drive will not work. The good news is that with the Partition Master tool on a bootable USB drive, you can resolve your issue. With it, you can partition a hard drive without an OS, format the hard drive, and even wipe the hard drive without an OS.