By AOMEI / Last Updated February 25, 2020

About MBR and GPT disk

Suppose you have a 4TB drive partition and accidentally initialize the disk to MBR, then there will be a 2TB waste. Because MBR disks only support up to 2TB partition size, once partition size surpasses 2TB, the excess part cannot be read or displayed. However, GPT disks are capable of a maximum 18EB partition.

In addition, MBR disk only allows four primary partitions at most, if more partitions are needed, you have to build a secondary structure known as extended partition and then you can create logical partitions. However, GPT disk allows 128 partitions which are similar to the primary partition of MBR.

As you see, GPT disks are more better than MBR disks. Except above said, partition on GPT disk has self-contained backup which is stored on the two ends of the disk. If one of the backups is destroyed, you can restore your disk with another. Therefore, converting disk which is accidentally initialized to MBR to GPT is a wise solution, to do this, you need a third-party software like AOMEI Partition Assistant to avoid data loss.

Convert MBR to GPT with AOMEI Partition Assistant

With data on your accidentally initialized hard drive, it’s risky to convert MBR to GPT with Disk Management. Because DM can only initialize a disk without any partition on it, or you must delete all partitions to get a totally unallocated disk so as to achieve the job with it. If you insist, a backup is needed to keep data safe and we recommend you AOMEI Backupper. Or you can choose AOMEI Partition Assistant to finish the conversion job without data loss. And before you do, please make sure your boot mode is UEFI which is required for GPT disk.

Step 1:Launch AOMEI Partition Assistant Profession. Select the data disk you want to convert and right click it. And then select "Convert to GPT Disk" in the drop-down menu.


Step2: Click "OK" after confirming the operation.


Step3:You can preview the conversion. To save the change, please click "Apply" on the toolbar.



  • For conversion between MBR and GPT disks on Laptop, please make sure the power supply is sufficient.

  • To ensure the data is consistent, do not abnormally terminate the program during the conversion process.

AOMEI Partition Assistant is a free and professional partition manager, supporting all Windows editions. With it, you also can resize C drive and merge two primary partitions, etc.