Can I Use mbr2gpt on Windows 10 Without a USB?
Asked by
Pockyish
I'm looking to convert my C drive from MBR to GPT so I can enable Secure Boot and upgrade to Windows 11. I'm not very familiar with mbr2gpt, but I've heard it's a non-destructive way to do the conversion. I already validated using the /allowFullOS command, but I'm unsure if that means I can safely convert MBR to GPT without needing a WinPE USB drive. Any advice would be greatly appreciated!
Answers
Just a heads up, are you certain that your drive is actually MBR? MBR has been pretty rare since Windows 8. You can check using the tutorial here: [Check if Disk is MBR or GPT](https://www.tenforums.com/tutorials/84888-check-if-disk-mbr-gpt-windows.html).
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Yes, you can definitely use mbr2gpt without a USB, just make sure there's enough free space on your drive to create a restore point. Here’s how you can do it:
1. Open the command prompt as an admin.
2. Run `reagentc /disable`.
3. Then execute `mbr2gpt /validate /allowFullOS`.
4. If it validates successfully, run `mbr2gpt /convert /allowFullOS`.
5. Reboot your system and go into the BIOS to set it to UEFI mode (instead of legacy).
6. Once you’re back on your desktop, run `reagentc /enable` to re-enable the system restore backups.
Just make sure to back up your data before making any system changes!
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Pockyish: Yes, I checked in Disk Management and confirmed it’s MBR. I remember there was an option during the Windows 10 setup that could have made it GPT, but I wasn’t aware of it back then.