When you have decided the disk itself must change style, DiskPart inside Windows Setup is the tool — and the whole job really does take about a minute. This page gives the exact command sequence for both directions, GPT to MBR and MBR to GPT. But it starts where every honest guide must start: with what the middle command destroys.
DiskPart conversion at Setup has a hard rule that explains the whole procedure: DiskPart will only convert an EMPTY disk. That is why every guide you have ever seen includes a clean step — and clean is not a gentle reset. It erases the entire physical disk instantly: every partition, every file, no recycle bin, no undo. On the right disk — empty, new, or backed up — this is the fastest fix in Windows installation. On the wrong disk it is the most expensive typo in computing. Confirm twice that this disk is safe to erase, then follow the sequence exactly.
Once clean runs, there is no going back, so the discipline happens before it:
diskpart and press Enter — wait for the DISKPART> promptlist disk — read the table. The Gpt column shows a star if the disk is GPT today; the Size column is how you identify your diskselect disk 0 — replace 0 with the number of the disk you verified by size. DiskPart answers Disk 0 is now the selected diskclean — this command erases the entire selected disk. DiskPart answers DiskPart succeeded in cleaning the diskconvert mbr or convert gpt — whichever matches your boot mode. DiskPart confirms the conversionexit, then close the Command Prompt windowDo not create partitions or click Format afterwards. Setup builds the correct partition layout for the new style on its own.
"The specified disk is not convertible" — this almost always means the disk still has partitions on it. DiskPart converts only empty disks. If you skipped clean, that is the cause — go back and run it, accepting that it erases the disk. On a genuinely empty disk, the same message can mean the device is not a fixed disk at all (for example you selected the USB installer itself or an SD card reader).
Nothing happens or the disk vanishes from the list — if list disk after clean no longer shows the disk, the drive or its cable/connection dropped. Exit, check the drive connection and power, and restart Setup. A disk that keeps disappearing is failing hardware, not a partition problem — stop converting and test the drive.
You will find tools and videos promising one-click conversion without data loss, sometimes even at the install screen. Be honest with yourself about the risk: any tool that rewrites a partition style in place is doing surgery on the map of your data, and if it fails halfway the disk is unreadable anyway. Inside Setup, Microsoft's own route is clean plus convert, and its guarantee is the opposite one — total erasure, totally predictable. If the data matters, the correct move is not a cleverer converter; it is to skip conversion entirely, boot Setup in the mode that matches the disk, and keep everything.
clean, erases the whole disk — every partition and every file — the moment you press Enter. It does not ask twice and it cannot be undone. Verify the disk number by size, and if this disk holds your only copy of anything, stop here and use the boot-mode fix instead.Watch the conversion done live — the Shift+F10 prompt, list disk, clean, convert, and the Refresh click that brings the disk back, exactly as written here.
▶️ Watch Full VideoClean removes the partition information instantly — the data is gone for practical purposes and the disk is ready to convert. Clean all additionally overwrites every sector with zeros, which takes a very long time on a big disk and is meant for securely wiping a drive before disposal. For an install fix, plain clean is correct; clean all only adds hours.
No. The message that the specified disk is not convertible simply means the disk still contains partitions, and DiskPart refuses to convert a disk that is in use. Nothing was changed. Run clean first — knowing it erases the disk — and the convert command will succeed.
No. Leave the disk as unallocated space and press Next. Windows Setup creates the correct system partitions for the style — EFI and MSR partitions on GPT, System Reserved on MBR — with the right sizes and formats automatically.