Change Master Boot Record into GUID Partition Table without Data Loss

You will learn the best alternative to DiskPart and Disk Management to change Master Boot Record to GUID Partition Table without any data loss.


By Michael / Updated on May 12, 2023

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About MBR and GPT

MBR and GPT refers to two different disk partition style. When you first initialize a new disk, the Computer Management will ask you to choose MBR or GPT. But some users don’t know much about them, here, you can briefly understand both of them.

MBR is short for Master Boot Record, uses the standard BIOS partition table. It ‘s produced earlier than GPT, so it can be compatible with the previous versions of the Windows OS. It supports creating a partition up to 2 TB. Besides, you can only create 4 primary partitions in a disk (or 3 primary partitions, an extended partition, and unlimited logical drives).

GPT, short for GUID Partition Table, is a new layout introduced with a Unified Extensible Firmware Interface (UEFI). It supports you to create partitions larger than 2 TB. And you can create up to 128 partitions per disk. Depend on the replication and cyclical redundancy check (CRC) protection, GPT can be more safe and reliable.

Therefore, if you need a larger drive size or you need more partitions, GPT (GUID Partition Table) is a better option. How to convert MBR to GPT? In the next part, you can get three methods to do it.


How to: Convert a disk from MBR to GUID partition table [3 ways]

Generally, there are 3 ways to change a master boot record disk into a GUID partition table disk.  When the disk you want to convert does not contain any partition, the Windows built-in Disk Management and Diskpart enable you to realize the conversion between MBR and GPT. In other words, it is a process of losing data.

If you don’t want to delete any stored data, the most convenient and safe way to convert MBR disk to GPT disk (or convert GPT disk to MBR disk) is using a 3rd party partition manager. Here, you can try AOMEI Partition Assistant, which can convert a disk between MBR and GPT without data loss.

Before changing your disk from MBR to GPT,  you should realize the following things:

Removable disks cannot be changed into a GPT disk.
Windows XP 32-bit cannot support GPT disks, and 64-bit can only use GPT disks for data.
Only 64-bit version of Vista and above on UEFI-based systems can boot from a GPT disk.

WAY 1: Change disk from MBR to GPT without data loss 

AOMEI Partition Assistant  Standard  is an all-on-one partition manager and magic disk tool which is designed for you to maintain and optimize your computer. It enables you to convert a data disk from MBR to GPT easily and safely in Windows 10, 8, 7. If the disk that you want to change contains an operating system, you need to upgrade AOMEI Partition Assistant Standard to a professional edition.. 


▪ You must be an administrator to do this in Windows.
▪ Before converting a disk, we suggest you close any programs that are running on or from that disk.
▪ To ensure the data is consistent, do not abnormally terminate the program during the conversion process.

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Step 1. Download,  install and launch it. Right-click the MBR disk you want to convert to GPT and select "Convert to GPT" in the drop-down menu or click the target disk and choose "Convert to GPT" from the right column.

Change Master Boot Record to GUID Partition Table

Step 2: It will ask you "Are you sure to convert the selected disk from MBR to GPT disk?". Click "OK" to confirm the change.


Step 3: To save the conversion, please click "Apply", and then click "Proceed" to perform the operation.


After the conversion is completed, you can create more primary partitions on GPT disk or add unallocated space (if disk is larger than 2TB) to existing partitions with AOMEI Partition Assistant. 

WAY 2: Convert a disk from MBR to GPT with built-in Disk Management

To open Disk Management console, please right-click "(My) Computer" and select "Manage" -> click "Disk Management". Windows built-in Disk Management tool allows you to convert a disk to GPT format as long as it is empty. If the disk contains any partitions or volumes, you will find "Convert to GPT Disk" option is greyed out. In such a case, you need to delete all partitions first.

Tip: Before you convert a disk, please make sure to back up anything that you do not want to lose on another hard disk.

Convert to GPT Greyed Out

Note: The following guide will result in data loss, please back up your important files before you convert a disk.

Step 1: Right-click the partition(s) on the disk you want to convert and select "Delete Volume".

Delete Volume

Step 2: After all the partitions or volumes are removed one by one, the disk will show as "Unallocated". Then, right-click the disk and select "Convert to GPT Disk". In an instant the disk has been converted from MBR to GPT.

Convert to GPT

Now you can re-create partitions and restore your backed up data to the GPT disk.

WAY 3: Change Master Boot Record to GUID partition table via Diskpart 

Like built-in Disk Management, Diskpart only supports changing a disk to GPT as long as it does not contain any partitions or volumes. So back up your data if you don't want to lose anything important.

Step 1: Click "Start Menu" -> input "diskpart" in the search box and press "Enter" -> Click "Yes" to launch command prompt.

Step 2: Input "list disk" and press "Enter" to display all disks on your computer.

Step 3: Input "select disk n" and press "Enter" to give a focus on the disk. n is the number of the disk you want to convert, and here take "Disk 1" for example.

Step 4: Input "clean" and press "Enter" to delete all partitions or volumes on the selected disk.

Step 5: Input "convert gpt" and press "Enter" to complete the conversion from MBR to GPT format.

Convert MBR to GUI partition table


Now, you’ve learnt the best way – using AOMEI Partition Assistant Standard - to change Master Boot Record to GUID Partition Table along with 2 other optional ways – using Disk Management or using DiskPart. The AOMEI product won’t cause any data loss in the course of the conversion while the other 2 tools require the deletion of all partitions on the target drive.

As for AOMEI Partition Assistant, if you want to use it on Servers, please try the Server edition.

Michael · Staff Editor
Michael is a professinal editor of AOMEI editor team.