Though converting Legacy BIOS to UEFI in Windows 10 is easy, there are a few things you should know and do before proceeding.

1. There will be no data loss while converting Legacy BIOS to UEFI. However, as a precaution, please back up your system.

2. You should be using Windows 10 v1703 or higher. If you are not sure, press Win + R, type winver and press Enter. On the second line you should see “version 1703” or higher.

3. The disk you are trying to convert should not have more than three partitions. If you have more than three partitions on the Windows 10 installation drive, either merge or delete excess partitions.

4. If you are using BitLocker to encrypt your system, decrypt the drive and disable BitLocker protection before starting the conversion process. With BitLocker protection turned on, Windows 10 cannot convert your drive from Legacy BIOS to UEFI.

5. After converting, you might have to change your motherboard firmware settings from Legacy BIOS to UEFI. Depending on your motherboard manufacturer, the procedure to switch from one to the other will be different. Have your motherboard manual handy to make things easier for you.

Check Whether You Are Using Legacy BIOS

The last thing you need to check is if you are using Legacy BIOS. After all, there is no use converting if you are already on UEFI.

To find out, search for “Create and format hard disk partitions” in the Start menu, and press Enter to open the built-in Disk Management tool. Now, right-click on the Windows installation disk and select “Properties.”

In the properties Window go to the “Volumes” tab. Here, if you see “Master Boot Record (MBR)” next to “Partition style,” you are on Legacy BIOS.

Convert Legacy BIOS to UEFI

Once you’ve confirmed you are on Legacy BIOS and have backed up your system, you can convert Legacy BIOS to UEFI.

1. To convert, you need to access Command Prompt from Windows advanced start-up. For that, press Win + X, go to “Shut down or sign out” and click on the “Restart” button while holding the Shift key.

2. The above action will reboot your system to the Advanced Start-up screen. Here, go to “Troubleshoot -> Advanced Options,” and select the option “Command Prompt.”

3. The first thing we need to do is validate the disk we are trying to convert. Type the below command and press Enter.

mbr2gpt /validate

If you see the “Validation completed successfully” message, then you can proceed to the next step. If you see any errors, your disk or system might not meet the conversion requirements.

4. After validating the disk, execute the below command.

mbr2gpt /convert

As soon as you execute, Windows 10 will start the conversion process, i.e. it will add all the required UEFI boot files and GPT components and then update the Boot Configuration Data.

5. Now restart your system, launch your motherboard firmware settings screen and change it from Legacy BIOS to UEFI. The procedure to change from Legacy BIOS to UEFI depends on your motherboard manufacturer. Consult the manual for the exact steps.

6. After booting into Windows 10, you can verify whether you are converted or not. Just like before, open the disk properties window from the Disk Management tool, and go to the “Volumes” tab. Here, you should see “GUID Partition Table (GPT)” next to “Partition style.”