What MBR and GPT are, and why you might want to switch
MBR (Master Boot Record) and GPT (GUID Partition Table) are two different ways of organizing how your hard drive stores information about where your files live. MBR is older — it dates back to the 1980s — and GPT is newer. The main practical difference: MBR can only handle drives up to 2 TB in size, while GPT works with drives of any size. If you have a newer computer or a large drive, your system may already use GPT. If you're using an older drive or an older computer, you likely have MBR.
You might want to convert from MBR to GPT if you're upgrading to a larger drive, moving to a newer motherboard that expects GPT, or preparing a drive for a newer operating system. Windows 11, for example, prefers GPT. The conversion itself erases everything on the drive, so you'll need to back up your files first and be prepared to reinstall your operating system.
Key Takeaways
- Converting MBR to GPT erases all data on the drive, so back up everything before you start.
- You can convert using Windows Disk Management (built into Windows), third-party tools like MiniTool Partition Wizard or Macrorit Partition Expert, or command-line tools like diskpart if you're comfortable with that approach.
- After conversion, you'll need to reinstall your operating system and restore your files from backup.
- Some older computers with BIOS firmware (rather than UEFI) cannot boot from GPT drives, so check your motherboard manual or BIOS settings before converting.
Checking whether your system can use GPT
Before you convert, verify that your computer's firmware supports GPT. Most computers built after 2010 use UEFI firmware, which works with GPT. Older computers use BIOS firmware, which does not. To check which you have on Windows, press Windows key + R, type msinfo32, and press Enter. Look for "BIOS Mode" — if it says "UEFI", you're ready to convert. If it says "Legacy", your system uses BIOS and cannot boot from a GPT drive.
On a Mac, GPT is the standard and has been for nearly two decades, so conversion is not necessary. On Linux, the answer depends on your bootloader and firmware, so check your distribution's documentation.
If your system uses BIOS and you need to use GPT anyway, you have two options: replace the motherboard with one that has UEFI firmware, or use the drive as a secondary (non-boot) drive for storage only. A secondary drive can be GPT regardless of your system firmware.
Backing up your data before conversion
Conversion to GPT destroys all partitions and data on the drive. Before you do anything else, copy every file you want to keep to an external drive, cloud storage, or another computer. This includes your operating system — you'll reinstall it after conversion.
Use Windows File Explorer or your system's file manager to copy folders, or use a backup tool like Macrium Reflect (free version available) or Windows Backup to create a full image of your drive. Store the backup on a drive that is not the one you're converting. Once you've verified the backup is complete and readable, you're ready to proceed.
Converting with Windows Disk Management
Windows includes a built-in tool called Disk Management that can convert MBR to GPT, but only if the drive is empty. If your drive has data or partitions, you must delete them first — which is why the backup step is critical.
To convert using Disk Management: right-click the Start menu, select "Disk Management", find your drive in the list, right-click each partition on that drive, and select "Delete Volume". Repeat until the drive shows as unallocated space. Then right-click the drive name itself (not a partition) and look for "Convert to GPT Disk". If that option does not appear, the drive may already be GPT, or your system firmware does not support it.
After conversion, the drive will be empty and ready for a fresh operating system installation. You'll need your Windows installation media (a USB drive or DVD with Windows on it) to reinstall.
Converting with third-party partition tools
Tools like MiniTool Partition Wizard (free version available) and Macrorit Partition Expert can convert MBR to GPT without deleting data first, which saves time if your drive is large or has many files. However, these tools still require that you back up first — conversion can fail, and if it does, data loss is possible.
Download the tool, install it, launch it, select your drive, and look for a "Convert MBR to GPT" or similar option in the menu. The tool will show you a preview of what will happen. Review it carefully, then proceed. The conversion usually takes a few minutes to an hour depending on drive size. After it completes, restart your computer.
These tools are generally reliable, but they are not made by Microsoft or your computer manufacturer. If something goes wrong, support may be harder to find. Use them only if you're comfortable troubleshooting on your own, or stick with Disk Management and accept that you'll need to reinstall your operating system.
Converting from the command line with diskpart
If you're comfortable with the Windows command prompt, you can use the diskpart tool to convert MBR to GPT. This approach is faster than the graphical tools and gives you precise control, but it offers no safety net — a typo can erase the wrong drive.
Open Command Prompt as Administrator (right-click the Start menu, select "Terminal (Admin)" or "Command Prompt (Admin)"), then type the following commands one at a time, pressing Enter after each:
- diskpart
- list disk (this shows all your drives; note the number of the one you want to convert)
- select disk X (replace X with the disk number)
- clean (this erases the drive)
- convert gpt
- exit
After the conversion completes, you can close the command prompt and proceed with reinstalling your operating system. Double-check the disk number before running the clean command — there is no undo.
Reinstalling your operating system after conversion
Once the drive is converted to GPT, it is empty and unbootable. You'll need to install Windows, macOS, Linux, or another operating system on it. For Windows, download the Windows installation media creation tool from Microsoft's website, create a bootable USB drive, insert it into your computer, restart, and follow the on-screen prompts to install Windows.
During installation, Windows will automatically create the partitions it needs on the GPT drive. You do not need to manually partition anything. After installation completes, restore your files from the backup you created earlier.
If you're converting a secondary drive (one that doesn't boot your system), you don't need to reinstall an operating system on it — you can simply format it as GPT and use it for storage. Right-click the drive in File Explorer, select "Format", choose a file system (NTFS for Windows, exFAT for cross-platform use), and proceed.
Frequently Asked Questions
Can I convert MBR to GPT without losing my files?
Third-party tools like MiniTool Partition Wizard claim to convert without data loss, and they sometimes succeed. However, conversion is a risky operation, and if it fails partway through, your files may be unrecoverable. Always back up before attempting conversion, regardless of which tool you use.
What if I convert and my computer won't boot?
This usually means your system firmware is BIOS, not UEFI, and cannot boot from a GPT drive. You can still use the GPT drive as a secondary storage drive, but you'll need to convert it back to MBR or replace your motherboard to use it as your boot drive. Check your BIOS settings or motherboard manual to confirm your firmware type before converting.
Do I need to convert if my drive is smaller than 2 TB?
No. MBR works fine for drives under 2 TB. Convert only if you're upgrading to a larger drive, moving to a system that requires GPT, or preparing for a newer operating system that prefers it. If your current setup works, there's no benefit to converting.
Can I convert an external USB drive to GPT?
Yes, the same methods work for external drives. Back up the data, use Disk Management or a third-party tool to convert, and then format the drive. External drives can be GPT regardless of whether your computer's boot drive is MBR or GPT.
How long does the conversion take?
Conversion itself usually takes a few minutes to an hour, depending on the tool and drive size. However, the full process — backing up, converting, and reinstalling your operating system — typically takes several hours. Plan for a full afternoon or evening if you're converting your main drive.