How To Convert an MBR disk to GPT in Windows 10 – Operating System 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 settings which can often speed up boot and shutdown times and provides additional security features.
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 Advanced Data Protection with a backup of the primary GPT header and partition entries that protects data on the disk in case of failure.

Steps to convert to GPT

1. Click Start and type Settings – select the first option

2. Navigate to Update & Security > Recovery

3. Select Restart now under Advanced startup

advanced startup settings

4. Select the Troubleshoot option

troubleshoot option in recovery environment

5. Select Advanced options

advanced option in recovery environment

6. Select the Command Prompt option

command prompt in recovery environment

Commands to Run

7. In the command prompt that comes up, enter the following in order to validate that the drive requirements are met. Press Enter on your keyboard to execute the command after it is typed in full exactly as written below.

mbr2gpt /validate

8. To convert the drive from MBR to GPT input the following command and press Enter

mbr2gpt /convert

9. Click the Close button on the top-right of the Command Prompt

10. Select Turn off your PC and let the system reboot.


Once restarting, the drive will begin a validation process and create an EFI system partition. This process could take upwards of an hour so let the system sit for a bit. UEFI boot files and GPT files will be added to the partition then the MBR2GPT tool will update the Boot Configuration Data (BCD) which will allow the system to boot correctly.

If you haven't already completed the Legacy to UEFI BIOS changes please follow this guide

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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