Using GParted to convert GPT to MBR without access to an OS

Question

I wiped my Windows 8 thinking I could install Windows 7 x86 but I can't because the disk is GPT. I need to convert to MBR.

I'm trying to use GParted to convert to MBR but it seems GParted can only do the opposite. Can GParted be made to convert to MBR?

Solution 1

Since you mentioned GParted, try this:

1. Launch GParted on the disk.
2. If any partitions are mounted (as indicated by a lock or key icon), unmount them.
3. Select Device->Create Partition Table.
4. Click Apply.

The disk should now use MBR. You can also create partitions within GParted, if you like; however, the Windows installer can do this automatically if you prefer.

Solution 2

For those of who who find this on a desperate google trawl like myself.

Inside the windows 7 installer, you can launch command prompt with CMD F10, then follow the previous post's advise with regards to diskpart...

Once you've entered the command prompt, type diskpart to enter the utility.

Type select disk # replacing "#" with the drive number of the one you wish to format. To see a list of disks, type list disk. Type clean. This deletes all volumes from the drive. Type convert mbr to convert the disk to mbr. Note: You can repeat this process and in step 3 replace with the command convert gpt to go back to GPT.

Comments

[Admin]

Thanks. Exciting news, but it said I need to use Windows 8 disc to repair; as soon as I click repair it said incompatible OS.

[Admin]

If that doesn't work you could use a partitioning tool like EaseUS Partiton Manager. It has a bootable version that supports conversion to and from GPT (it also has support for doing so without data loss).

[Admin]

I didn't try this method but it works. I believe your method will work so I will also upvote.

[Admin]

From @JasonErickson: You can clean the disk with diskpart by booting any windows Vista,7,8.x,2008.x,2012.x install media. When the welcome screen comes up press "Shift+F10" and it will bring up a command prompt window. Then type diskpart. Then follow the previous directions to clean the disk and convert to MBR. This is an alternate route to diskpart.

[fixer1234]

This is a repeat of the @Moses answer. It just gives an alternate route to access diskpart. That minor variation should just be noted as a comment on the other answer, which you need a little more rep for. I've moved the information there so it isn't lost if your answer gets deleted. This answer would be considered low quality because it doesn't add something significant to what has already been posted, so people could downvote it. You might want to delete it so any downvotes don't eat into your rep.

[hanshenrik]

This only works if MBR happens to be the default partition table for the verson of gparted you're using... i don't think its the default in Ubuntu 14.04's gparted :o (GPT now i think?)

[Rod Smith]

MBR (GParted calls it "msdos") is the default in every version of GParted I've used, including the one in Ubuntu 14.04. You're right to point out that it might change (or even have changed) at some point, though. If so, the partition table type can be changed in the dialog box that appears after you perform step #3 in my procedure; simply change it in the "Select new partition table type" field.

[Admin]

If you can't see the "Command Prompt" option, press [shift]+[F10] to enter CMD