By Teresa / Last Updated June 28, 2021

When need to convert system disk to GPT?

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. Well, sometimes, you might want to convert boot disk from MBR to GPT 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 MBR table will make the left storage unallocated and cannot be used. As the disk storage increasing, it is rather common to see spacious drive on the market.

▶Maximum primary partition numbers: a distinct limit of 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 of primary partition).


Possibly, there is another reason forces you to convert boot drive from MBR to GPT. For example, when installing Windows 8.1 or Windows 10, you’ll get “the selected disk is not of GPT style” error and cannot install any more. Then, what should you do?

Convert system disk to GPT without losing data in Windows (2 Ways)

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”.

Tip: 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 fails you. 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 disk and does not have magic 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

AOMEI Partition Assistant Professional is such a great tool, which will assist you 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 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. You can download its demo version for a free trial.

Download Demo Win 10/8.1/8/7/XP
Secure Download

How to convert boot drive to GPT with secure boot 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.

Notice: If you want to covert 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.

Step 1: Convert MBR system disk 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.


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 orF2 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.

Important: 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 in Windows 10/8/7. 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 quick partition a hard drive, write zeros to wipe data on hard disk, change serial number, manage hard drives from 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.