How To Convert an MBR disk to GPT in Windows 10 – Storage Disk

Why you need this article

GUID Partition Table (GPT) takes advantage of the Unified Extensible Firmware Interface (UEFI), accommodating devices larger than 2TB and allows as many partitions as you may need. Windows 10 can utilize UEFI BIOS setting which can often speed up boot and shutdown times and provides additional security.
Master Boot Record (MBR) is now considered a legacy configuration and has a number of limiting factors making it far less desirable for any storage devices currently used in your system.

GPT can offer faster boot speeds and operating system load time over traditional MBR BIOS boot configurations. GPT has better operating system compatibility with Windows/Linux OS, and it also offers advanced data protection with a backup of the primary GPT header and partition entries which can help protect data on the disk in case of a failure.

Master Boot Record (MBR) GUID Partition Table (GPT)
2TB (for 512B sector) No disk capacity limit
Maximum 4 partitions. Maximum 128 partitions
BIOS(Legacy boot) UEFI


Windows Server 209/2016/2012/2008

Windows 10/8/7, Linux
Windows Server 2019/2016/2012/2008
Windows XP/Vista (64bit for data only)
macOS and modern Mac OS X

Identifying MBR vs GPT disks

These steps will help you identify which disks are currently set to MBR and need to be converted to GPT.

1. Select the Start button then type Disk Management – select the first option

2. Right click each Disk in the bottom left and select Properties

3. Select the Volumes tab

4. The Partition Style section will identify either

– Master Boot Record (MBR)


– GUID Partition Table (GPT)

How to convert storage drives

Using Disk Management

1. Select the Start button and type Disk Management – select the first option

Create and Format hard disk partitions

2. In the new window identify which disk you wish to convert

3. Right click each partition currently listed on the disk then click Delete Partition or Delete Volume

4. Right click the Disk you want to convert and select Convert to Dynamic Disk

Using Command Line

1. Select the Start button then type Command Prompt

2. Right click the returned result then select Run as Administrator

3. Type diskpart and hit enter on the keyboard

4. With DISKPART prompt visible, type list disk and hit enter on the keyboard​​​​​​​

Make note of the disk number you wish to convert

5. Type select disk disk 1 and hit enter on the keyboard

Replace disk 1 with whatever disk number you noted after step 4

6. Type clean and hit enter on the keyboard

7. Type convert gpt and hit enter on the keyboard

This process will identify the disk we wish to convert to GPT, format and remove all partitions then convert the disk from MBR to GPT.

How to convert an OS disk – inside OS

To convert an operating drive from MBR to GPT within Windows 10, follow these steps:

1. Select Start and type Command Prompt

2. Right click the returned result then select Run as Administrator

3. Type the following command into the new window

mbr2gpt /validate /allowFullOS

One of two results will output: Failed or completed successfully

If the process completes successfully your drive is ready for a conversion

If the process fails, the drive is already registering as GPT

If the process completed successfully proceed to the next step

4. Type the following command

mbr2gpt /convert /allowFullOS

The tool will attempt to convert the drive into GPT

5. Restart the computer and make sure your BIOS is set to UEFI mode


This article covers How to convert storage drives and How to convert an OS disk to GPT. Each task will take a bit of time and patience but if done correctly should be a fairly straightforward and simple process.

Follow these articles if you wish to:

Convert an Operating System MBR Disk to GPT

Convert BIOS From Legacy to UEFI

We hope this article was useful and as always, please don't hesitate to reach out to your Puget Systems Support Technician with any questions.

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