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Gimbroel's avatar
Gimbroel
Iron Contributor
Jun 18, 2025

Safe way to convert mbr to gpt without formatting on windows 10?

Hi all, I have an old Windows 10 PC (10 yrs old) and I can't upgrade Windows 10 to Windows 11 because the disk is formatted by MBR. Windows 11 installation asks me to format the hard drive to GPT as...
Treysil's avatar
Treysil
Iron Contributor
Jun 18, 2025

Converting an MBR to GPT without data loss on Windows 10 is possible using built-in tools, but it requires careful steps. Here's a safe method using Microsoft's MBR2GPT tool, which is designed for this purpose:

How to convert MBR to GPT (Using MBR2GPT):
Note: This tool is available in Windows 10 version 1703 and later.

1. Open Command Prompt as Administrator:  
Press Windows + X and select Command Prompt (Admin) or Windows PowerShell (Admin).

2. Validate the Disk:
Run the following command to validate if the disk is suitable for conversion:  
mbr2gpt /validate /disk:<disk_number> /allowFullOS
Replace <disk_number> with the disk number you want to convert.
To find the disk number, open Disk Management (diskmgmt.msc).

3. Convert MBR to GPT:
If validation passes, run:  
mbr2gpt /convert /disk:<disk_number> /allowFullOS

4. Reboot and Change Boot Mode:
After conversion, you'll need to switch BIOS mode from Legacy to UEFI in your system firmware settings.

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