[Question] Windows 11: GPT or MBR?

Microsoft's Windows 11, which has been released on October 5, 2021, provides users with a new UI interface as well as a number of unique features geared to accommodate the current mixed working environment. Microsoft has declared that Windows 11 will pay more attention to user data security and work effectiveness, thus the hardware requirements for Windows 11 will become more stringent, which will be difficult for certain obsolete devices.

But, some users are confused when they try to install or upgrade to Windows 11. It seems like Windows 11, unlike Windows 10 which can use MBR and GPT disk as system disk, only allows users to use a GPT disk as the system disk.

Why is GPT partition scheme as a system disk necessary? If you don’t know much about this, let’s learn some basic information about partition style at first.

Windows 11—GPT VS. MBR

In Windows OS, if you need to use a new disk, you must initialize it. During the process, the system will ask you to choose a partition type. There are only 2 options: MBR and GPT.

▶ Overview of MBR partition style

MBR, or Master Boot Record, is a conventional disk partitioning style that begins with an MBR table boot sector. This partition table contains information on file system partitions and the codes needed to perform your commands.

The capacity of the partition or disk cannot exceed 2TB since the MBR partition table utilizes 4 bytes to represent the total number of sectors of the partition, which may be stated up to the 32nd power of 2 and 512 bytes per sector. And the MBR partition table is restricted in capacity and can only hold information for 4 primary partitions. As a result, MBR drives may create up to 4 main partitions.

Furthermore, on an MBR drive, the partitioning and boot data are kept in the same location. If one of them is broken or corrupted, you will lose all of your data, which will be tough to restore.

▶ Overview of GPT partition style

GPT disks are partitioned using GUIDs (Globally Unique Identifiers). It is not limited in terms of capacity or the number of divisions. The biggest GPT disk may be up to 18TB in capacity, and users can construct up to 128 partitions.

A partition on a GPT disk has a self-contained backup at the end of the disk. If one of them is damaged, you may restore it from the backup, keeping your machine secure.

What’s more, the head of a GPT disk is known as "Protective MBR," which improves compatibility for old BIOS PCs if users want to use GPT disks.

Does Windows 11 need GPT or MBR?

In fact, the answer to this question is determined by the boot mode.

One of the distinctions between Windows 11 and earlier Windows operating systems, according to Microsoft's official release, is that Windows 11 only supports booting through UEFI, the most recent version of boot mode.

The boot mode describes how the motherboard's firmware locates the boot software following the power-on self-test. There are two modes: Legacy (BIOS + MBR) and UEFI (UEFI + GPT). UEFI requires an EFI driver, which can only be generated on a GPT disk. Because GPT boots the system differently than MBR, using the standard system installation technique may result in a 'Cannot be installed to this drive' error.

This is why Windows 11 only supports GPT disk as a system disk.

How to convert disk from MBR to GPT without data loss for Windows 11?

Given that UEFI requires a GPT disk to boot a system, if your current system disk is an MBR disk, you'll need to change this MBR disk to GPT style before upgrading to Windows 11. Without a doubt, Windows' built-in utilities will prompt you to delete all partitions and data; if you do, please make a backup of the target drive.

AOMEI Partition Assistant Professional is an outstanding disk and partition manager for Windows 11/10/8/8.1/XP/Vista users to get over these limitations. Unlike Disk Management, which needs users to clean the target disk before conversion, this reliable tool's "Convert to GPT Disk" function allows you to convert the system disk from MBR to GPT while maintaining data security.

Step 1. Install and open AOMEI Partition Assistant Software, right-click the MBR disk you want to convert, and select "Convert to GPT".

Step 2. In the pop-out window, you will be asked if are you sure to convert the selected disk from MBR to GPT disk. Click "OK" to continue.

Step 3. After a while, you will back to the main console, click "Apply" and you will find your disk style has been changed into GPT.

Now the disk is a GPT disk, you can use it to upgrade your PC to Windows 11. Don’t forget to change the boot mode to UEFI mode in BIOS.

To sum up

Now you know Windows 11 needs GPT or MBR. If you wish to upgrade in the Microsoft-recommended manner, you must first convert MBR to GPT and then remember to change Legacy to UEFI.

AOMEI software can help manage your partitions well by providing you with various effective functions such as moving applications from one partition to another, converting file systems between FAT32 and NTFS, converting the primary partition to the logical drive, etc. What’s more, it has the Server Edition for Windows Server users to easily manage Windows Server 2022/2019/2016/2012(R2)/2008(R2).