Convert MBR Disk to GPT Disk

In Disk Management

1. Open the Control Panel (icons view), and click on the Administrative Tools icon, then close the Control Panel window.

2. Click on Computer Management in Administrative Tools, then close the Administrative Tools window.

3. If prompted by UAC, click on Yes.

4. In the left pane under Storage, click on Disk Management. 

 5. In the disk (ex: Disk 1) that you want to convert to a GPT disk, right click on each partition and volume on the disk and click on Delete Volume until the whole disk is unallocated space. 

6. Right click on the disk (ex: Disk 1) that you want to convert to a GPT disk, and click on Convert to GPT Disk. 

7. When finished shortly, you can confirm that the disk is a GPT disk if you right click on the disk and it has Convert to MPR Disk instead now.

In a Command Prompt

1. Open an elevated command prompt, and go to step 3 below.

OR

 2. Open a command prompt at boot, and go to step 3 below.

3. In the command prompt, type diskpart and press enter. (See screenshot above)

4. Type list disk and press enter.
NOTE: Make note of the disk number (ex: Disk 1) that you want to convert to a GPT disk.

5. Type select disk # and press enter. 
NOTE: Substitute # with the actual disk number that you want to convert to a GPT disk. For example, select disk 1.

6. Do step 7 or 8 below for what you would like to do.

7. To Use the "Clean" Command to make Disk Unallocated
NOTE: This is the easiest method. It will wipe the disk clean all at once leaving it as unallocated space afterwards.

A) In the command prompt, type clean and press enter.

B) Go to step 9 below.

8. To Manually make Disk Unallocated
NOTE: This method has you manually delete each volume on the disk before converting the disk to GPT.

A) Type detail disk and press enter. If the disk does not have any volumes listed, then you can go to step 8Ebelow.
NOTE: This will give you a list of all the volume numbers on the selected disk number that you will need to delete in steps 7 and 8 below.

B) Type select volume # and press enter.
NOTE: Substitute # with a volume number listed in step 8A. For example, select volume 3.

C) Type delete volume and press enter.

D) Repeat steps 8B and 8C for each volume # listed in step 8A until you have deleted all volume #'s.

E) When done, type select disk # and press enter.
NOTE: You would use the same one from step 5 above. For example, select disk 1.

11. Type convert gpt and press enter.


Note: Shift+F10 to open an Command Prompt on Windows during windows installation