How to Convert System Disk to GPT without Losing Data?

Need to convert system disk to GPT, but not want to reinstall the OS? Here, you can learn how to convert MBR system disk to GPT without losing data or Windows operating system in Windows step by step.


By Emily / Updated on March 6, 2024

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When need to convert MBR system disk into GPT?

It is known to all there are two popular partition schemes for hard drives, MBR and GPT, both of which define how information is structured on the partition. GPT is a newer standard that provides more options than the traditional MBR partition table that is common in computers. And Microsoft now officially proclaimed that the UEFI and GPT are required if you upgrade Windows 10 to Windows 11 via the "Check for Update" feature.

MBR is more compatible yet the “Protective MBR” on the GPT partition table protects data on the disk from being overwritten when using old tools. Well, sometimes, you might want to convert system to GPT without losing data for the following factors:

▶ Disk capacity of your hard drive: in general, it is suggested to use GPT style if the disk is bigger than 2TB because the MBR table will make the left storage unallocated and cannot be used. As disk storage increases, it is rather common to see spacious drives on the market.

▶ Maximum primary partition numbers: a distinct limit of the MBR partition table is that it allows you to create only up to 4 primary partitions, or 3 primary partitions plus unlimited logical drives. While GPT supports up to 128 primary partitions (all partitions are primary partitions).


Possibly, there is another reason that forces you to convert the boot drive from MBR to GPT. For example, when installing Windows 11, you’ll get a “the selected disk is not of GPT style” error and cannot install anymore. Then, what should you do? This post aims to show you how to convert system disk to GPT without losing data.

Convert system disk to GPT without losing data via MBR2GPT.exe

Where there is a demand, there is a market. Certainly, there are programs to help you solve MBR and GPT conversion issues. First of all, you can make use of the MBR2GPT.exe, embedded in Windows OS after Windows 10 Creator’s Update v1703. This program is located in the Win\System32 directory and has to run in Command Prompt. MBR2GPT is designed to convert system disk instead of data disk on Windows 10 v1703 or later, without modifying or deleting data on the disk. So, you can refer to the steps below to convert the MBR system disk to GPT without losing data.

▶ Within Windows: type “mbr2gpt /convert /allowfullos”.


Note: Type in “mbr2gpt /convert /disk 0 /allowfullos” if there is more than 1 disk on the computer, and 0 stands for the system disk number.

▶ Within Windows PE: type “mbr2gpt /convert /disk n”.

You need to change legacy to UEFI in BIOS after converting. So, make sure your computer’s motherboard supports UEFI mode.

Simple as it is, sometimes you may find it lets you down. Here are detailed reasons:

✍ It only works in Windows 10 v1703 and later. What if you run Windows 10 previous version or another Windows OS like Windows 7 or 8?

✍ It converts only system disks and does function on data disks.

✍ It works through command prompt which may not be easy to use for common users.

To make things easier and viable, you can try the second solution.

Convert MBR system disk to GPT without data loss via professional software

Theoretically, Disk Management and Command Prompt can also convert disk, however, both tools will ask users to clean the disk. Since the target disk is the system disk, these tools are not allowed users to convert system disk to another partition scheme.

AOMEI Partition Assistant Professional is such a great tool, which will assist you to convert both system disk and non-system disk from MBR to GPT without deleting partitions or volumes. Converting GPT back to MBR is also available.

The software works great on Windows 11, Windows 10, Windows 8/8.1, Windows 7/Vista, and Windows XP (every version). You can create bootable media to convert system disk to GPT without booting Windows as well. It has a graphical user interface that is friendly to both computer novices and experts. You can download this tool to see how to convert boot drive from MBR to GPT.

Download Pro Demo Win 11/10/8.1/8/7
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Converting MBR boot disk to GPT with this software can be done in two parts, MBR to GPT conversion and then Legacy to UEFI configuration. First of all, backup any important files to a safe place because data loss might be caused by inappropriate operations or other unexpected accidents.

Note: If you want to convert without Windows OS, you need to create a bootable USB drive first, and then boot up your computer with the USB flash drive. AOMEI Partition Assistant is preinstalled.

Section 1: Convert MBR to GPT without reinstalling Windows

1.1 Install and launch AOMEI Partition Assistant. Right-click the system disk and select “Convert to GPT" or click the disk and choose "Convert to GPT" from the right column.

Convert System Disk To GPT

1.2 There are confirming page and an information page. Choose the positive one to continue.


1.3 Finally, click “Apply” and later “Proceed” to convert MBR system disk into GPT.


Please note that this process will be done after a reboot. When the progress completes, shut down your computer.

Section 2: Enable UEFI boot mode in BIOS

2.1 Once start up the computer, keep tapping Del on a desktop or F2 on a laptop to bring out the BIOS menu. If it does not work, you can press Esc to enter the full menu where you can find the BIOS option.

2.2 Navigate to the Boot tab and you can switch from Legacy to UEFI here.

Legacy to UEFI

2.3 Press F10 to save changes and exit BIOS.

Important: As stated, you have to make sure that your computer supports UEFI boot mode.


Thanks to these great utilities, we can convert system disk to GPT without losing data. Converting MBR to GPT on data disk is also available with AOMEI Partition Assistant Professional. If you're an administrator of a company or enterprise user, it would be a good choice to try its Unlimited license.

Both tools are great, but with AOMEI Partition Assistant, you are likely to have more possibilities. For instance, you can quickly partition a hard drive, write zeros to wipe data on a hard disk, change serial numbers, manage hard drives from the command prompt, etc. Further, you can convert system disk to GPT without data loss on Server 2012 with its Server edition. Go ahead to discover more.

Emily · Staff Editor
Emily is an English editor of AOMEI Technology; she has a great passion for providing easy solutions for people to tackle with all disk or partition management problems. In addition to writing articles about disk/partition management, she also edits great tutorials on how to back up and restore disk for data security. In her spare time, she loves to learn computer skill to improve herself or stay with her family to enjoy a good day.