How can I change mbr to gpt without data loss?

 The built-in tool can convert mbr to gpt and all data on the disk will be deeleted.

You're thinking about changing from MBR to GPT without losing data — nice move, but gotta be careful. Don’t just jump in with any partition tool. Use reliable ones like Disk Management (built-in), or third-party tools. Some tools are buggy or buggy enough to cause data loss. Make sure your motherboard and BIOS support GPT (most modern stuff does, but older BIOS systems might not). If your BIOS is BIOS instead of UEFI, switching to GPT might cause boot issues.

If it’s your boot drive (where Windows is installed), you need to do a GPT conversion in UEFI mode. Doing it in Legacy BIOS mode can brick your OS. Also, for a system disk, use tools like Microsoft’s MBR2GPT utility — don’t just try to convert with third-party tools blindly. After changing MBR to GPT without losing data, make sure to switch your BIOS from Legacy to UEFI mode if needed. If you forget, your system won’t boot.

Your disk should be partitioned properly after conversion. For example, if you have multiple partitions, make sure they’re all intact and correctly formatted. Every tool has its quirks. Read the documentation. For example, MBR2GPT has specific steps and requirements, like having a system partition with enough space, no other OS installed on the same disk, etc.

Safety checklist for converting an MBR Disk to GPT without data loss.

Create a Verified Backup

Make a full image of the disk.

Test-restore at least one file to confirm the backup isn’t corrupt.

Confirm Windows & Firmware Compatibility

Windows 10 version 1703 or later (or Windows 11) is required for mbr2gpt.exe.

Check that your motherboard supports UEFI boot (and know how to switch to it after conversion).

Check Disk Health First

Run chkdsk /scan or chkdsk /f to ensure no file-system errors.

Optionally run the drive maker’s SMART diagnostic—converting on a failing disk is risky.

Audit Your Partition Layout

1. Press Win + X → Disk Management (or use diskpart → list partition).
2. On mbr2gpt.exe targets: make sure there are ≤ 3 primary partitions and at least 100 MB of free space for the future EFI System Partition (ESP).
3. For GUI tools ensure the disk isn’t part of a dynamic-disk set or storage pool.

Suspend Write-Blocking Features

BitLocker: manage-bde -protectors -disable C: (resume after the reboot).

Any real-time antivirus or third-party disk-protection utilities should be paused temporarily.

By following the above rules, it will be more safe to change mbr to gpt without data loss on any Windows PC.

Even though MBR2GPT is pretty reliable when you change MBR to GPT on Windows PC, there's always a tiny chance something could mess up during the conversion. I've seen folks run into boot issues or partition problems if they didn't follow the steps carefully. Some older BIOS systems might not support booting from GPT disks. Make sure your motherboard and firmware are UEFI-compatible, or you might end up with a disk you can't boot from.

You mentioned having a backup before changing MBR to GPT, which is smart. I can't stress enough — if something unexpected happens, you’ll thank yourself for the backup. The tool requires a certain partition layout and free space for the conversion. If your disk is heavily partitioned or has weird setups, you might run into issues. Sometimes, after switching, Windows might not boot right away or might need some repair. Be prepared to run startup repair or fix boot records if needed.

While MBR2GPT is designed to be safe, reversing back from GPT to MBR isn't straightforward and can be risky or require data loss. I’ve used MBR2GPT a couple of times on clean installs or test systems — it works well if you follow the instructions carefully. But if your system is a bit funky or has lots of custom partitions, it’s worth doing some more research or even considering a fresh install just to be safe.

DiskGeniius Pro, an all-in-one disk-management suite for changing MBR to GPT without losing data in Windows 11. Beyond the usual partition-resize, clone, and surface-test tools, it adds powerful extras undelete, full-image backup, hex editor, RAID reconstruction, and a WinPE builder. 

A standout convenience is its ability to switch a disk’s partition style between MBR and GPT without re-formatting, so you can adopt UEFI or create more than four primary partitions while keeping every byte of data intact.

Great question! From my own experience, changing MBR to GPT — especially if you're doing it with third-party tools or manually — can be a bit risky if you're not super careful. In real life, I’ve seen folks lose data or run into boot issues because they didn’t back up first or because the conversion process went wrong. Even with trusted tools, things can sometimes get messy if there's a power outage, hardware failure, or if the disk has bad sectors.

My advice

• Always backup everything important first. Like, really, do it. External drive, cloud, just do it.
• Make sure your system is stable — no power interruptions during the process.
• Double-check that your hardware supports UEFI boot mode if you want to boot from GPT.

In the end, how to change MBR to GPT, if you're cautious and prepared, the risk is manageable. But if you’re not experienced or don’t want to take chances, maybe get a professional involved or stick with official tools.

Indeed, MBR2GPT.exe is a popular command line tool provided by Microsoft in Windows 10 and Windows 11. It converts a disk from MBR (Master Boot Record) to GPT (GUID Partition Table) without losing data. This tool is mainly used to prepare systems for UEFI boot mode, which is required for features like Secure Boot and Windows 11 installation.

It's typically used when upgrading from BIOS to UEFI, especially for modern hardware or during in-place OS upgrades.

However, there are the most common issues and problems when you use it to convert or change mbr to gpt in Windows, along with brief explanations and possible solutions.

Issue 1. "Disk layout validation failed for disk 0"

Cause: The disk does not meet the layout requirements in order to change mbr to gpt without data loss.

Fix:

Ensure the disk uses MBR and has a maximum of 3 primary partitions.

Delete any unnecessary recovery or OEM partitions if needed.

Use diskpart to check partition structure:

diskpart
list disk
select disk 0
list partition

Issue 2. "MBR2GPT cannot find OS partition(s)"

Cause: The tool can't find a valid Windows installation.

Fix:

Make sure the system partition is marked as active and contains boot files.

Boot from Windows PE or recovery media if running inside Windows fails.

Try using the tool with the /allowFullOS flag if you’re running it from a live OS.

3. BitLocker Errors

Cause: BitLocker encryption can prevent the conversion.

Fix:

Suspend BitLocker before running the tool:

manage-bde -protectors -disable C:

Changing a disk from MBR to GPT without data loss is possible using certain tools and methods, but it carries some risks. Before proceeding, it's highly recommended to back up your important data to prevent any accidental loss.

Methods to change MBR to GPT without data loss:
1. Use Microsoft's MBR2GPT Tool (Built-in Windows 10/11)
Microsoft provides a free tool called MBR2GPT that can convert a disk from MBR to GPT without deleting data. This tool is available in Windows 10 version 1703 and later.

Prerequisites:

• The disk is the system disk (boot disk).
• The disk has enough space and a compatible partition layout.
• You have a recent backup, just in case.

Steps:
1. Open Command Prompt as Administrator:
Press Windows + X → select Command Prompt (Admin) or Windows PowerShell (Admin).

2. Validate the disk:
Run: mbr2gpt /validate /disk:<disk_number> /allowFullOS
Replace <disk_number> with the correct disk number (usually 0 for the main disk). You can find it using diskpart:
diskpart
list disk
exit

3. Convert the disk:
Run: mbr2gpt /convert /disk:<disk_number> /allowFullOS

4. Reboot your PC:
After conversion, restart your PC and enter BIOS/UEFI.
Change the firmware mode from Legacy BIOS to UEFI if needed.

Note: If your system is using BIOS mode, you'll need to switch to UEFI mode after conversion.