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

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?

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.

If you have a Windows 7 Installation disk, you can enter Repair mode and use diskpart to accomplish this.

From Windows 7 DVD, click Repair your computer when you see this screen:

Then select Command Prompt in the Repair window:

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

1. Type select disk # replacing "#" with the drive number of the one you wish to format. To see a list of disks, type list disk.
2. Type clean. This deletes all volumes from the drive.
3. 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.

Sources: Change a GUID Partition Table Disk into a Master Boot Record Disk, Change a Master Boot Record Disk into a GUID Partition Table Disk

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.