How to Convert MBR System Disk to GPT without Losing Data?

September 21, 2017

In the trouble of losing data when converting MBR system disk to GPT partition scheme? Don’t worry. You’ll learn how to convert your system disk to GPT without data loss here.

GPT vs MBR: which is better for your system disk?

It is known to all there are two popular partition schemes for hard drive, MBR and GPT. A partition scheme defines how information is structured on the partition. GPT is a newer standard which provides more options than traditional MBR partition table that is common in computers. MBR is more compatible yet the “Protective MBR” on GPT partition table protects data on the disk from being overwritten when using old tools. Anyway, you can learn more difference between them in GPT and MBR.

Well, when it comes to choosing partition style for your system disk, you can take following factors into consideration.

  • Disk capacity of your hard drive: in general, it is suggested to use GPT style if the disk is bigger than 2TB, because MBR table cannot work with disk larger than 2TB. As the disk storage increasing, it is rather common to see spacious drive on the market.

  • The number of primary partition: a distinct limit of MBR partition table is that it allows you to create only up to 4 primary partitions. Surely, there is no limit for logical drive in extended partition on MBR. GPT disk partition is not constrained by temporary schemes.

Possibly, there is other reasons force you to convert MBR to GPT. For example, when installing Windows 8.1 or Windows 10, you’ll get “the select disk is not of GPT style” error and cannot install any more. Then, what should you do?

Utilities to convert system disk to GPT without losing data in Windows

Where there is a demand, there is a market. Certainly there are programs to help you solve MBR and GPT conversion issue. This article introduces two easy-to-use tools for you, Windows built-in tool and powerful 3rd party conversion tool.

Windows 10: convert system disk to GPT via MBR2GPT.exe

Since Windows 10 Creator’s Update v1703, there is MBR2GPT.exe program embedded with. This program locates in Win \System32 directory and has to be 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 steps below to convert MBR system disk to GPT without losing data.

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

Tips: You need to change legacy to UEFI in BIOS after converting. So, make sure your computer’s motherboard supports UEFI mode. You can learn more specific steps with screenshots in MBR2GPT Windows 10. Possible conversion fail causes are also explained there.

Simple as it is, sometimes you may find it fails you. First, 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? Second, it converts only system disk and does not have magic on data disk. Third, 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

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

AOMEI Partition Assistant Professional works great on Windows 10 (every version), Windows 8/8.1, Windows 7/Vista and Windows XP. You can create bootable media to convert system disk to GPT without booting Windows as well. It has graphical user interface which is friendly to both computer novice and expert. Keep reading to learn more.

How to convert system disk to GPT and boot successfully in two steps?

Converting MBR 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.

Step 1: Convert MBR system to GPT without data loss

1.1 Install and launch AOMEI Partition Assistant. Right click the system disk and select “Convert to GPT Disk” at the main interface.

Convert System Disk to GPT

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

MBR to GPT convert confirm

1.3 Finally, click “Apply” and later “Proceed” to execute the pending operations.


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

Step 2: Enable UEFI boot mode in BIOS

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

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

Legacy to UEFI

2.3 Press F10 to save changes and exit BIOS.

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


Thanks to these great utilities so that we can convert system disk to GPT without losing data. Both tools are great, but with AOMEI Partition Assistant, you are likely to have more possibilities. For instance, you can change file system without formatting as well. Further, you can convert system disk to GPT without data loss on Server 2012 with its Server edition. Go ahead to discover more.