How to Change Legacy to UEFI without reinstalling

How to Change BIOS from Legacy to UEFI

Once you’ve made sure everything is in order, it’s time to use the MBR2GPT tool.

Search for cmd in the Start Menu, right-click, and select Run as administrator. Your disk must meet the conversion requirements for the MBR2GPT tool to be able to convert it. Check if it does by validating the disk using the following command:

mbr2gpt /validate /disk:0 /allowFullOS

If the disk you want to convert is not disk 0, replace 0 with the appropriate disk number.

If your disk doesn’t meet the conversion requirements, you’ll see an error. For instance, the following error resulted from validating a USB drive.

If the validation was successful, run the following command to begin the conversion:

mbr2gpt /convert /disk:0 /allowFullOS

Let the conversion run, it should only take a few seconds.

Restart your PC and go into your motherboard’s firmware to change the settings. Assuming you already figured out how to enter the BIOS before starting the process, this should take only a few seconds. In most cases, you’ll see an option to select the Boot mode under the Boot tab/section in your firmware.

Boot into Windows. Verify that you’ve successfully converted the partition using the same process you used earlier. Head to the Disk Management app, right-click on the converted disk, select Properties > Volume, and this time around the Partition style should be GUID Partition Table (GPT).