By Catherine / Last Updated August 19, 2019

With the development of technology, the size of hard drive become bigger and bigger. The capacity of hard disk eventually up to TB. A 3TB hard drive is very common now. When you get a 3TB hard drive, such as Seagate Desktop 3TB HDD, Western Digital Caviar Green 3TB, Hitachi Deskstar 7K3000 3TB... then drop it into your computer, your computer will ask you whether want MBR or GPT formatting?

Because a MBR disk has a 2TB limit. MBR is the old way of partitioning. GPT is a just newer way, which can create theoretically unlimited partitions on the hard disk, even though it is generally restricted to 128 partitions by most OSs. Unlike MBR that limits 4 primary partitions per hard drive. So, if you hope your hard drive show as a full 3TB, you should format your 3TB hard drive to GPT.

However, some people forget to format the 3TB hard drive as GPT when they install OS. As a result, the Windows system can only see around 2 TB of space and get around 750GB of unallocated space. Then how to change this situation if you want to fully use the 3TB hard drive? You don’t want to reinstall OS. Don’t worry, there are two ways to solve this problem.

One is with diskpart.exe, proceed as follows:

Click "Start" menu, type "diskpart" in the searching box. Press enter and open the diskpart.exe.

  • Input "list disk", all disk will be shown.

  • Select the disk you want to convert by typing "select disk x".

  • Input "detail disk", disk detail will be shown.

  • Select volume x.

  • Delete volume x.

  • Select disk x.

  • Type convert gpt and press enter.

This method can realize the conversion between MBR and GPT, but with a great data loss. Therefore, many users have been searching for a partition assistant, which will not cause data loss. That is another solution with the help of AOMEI Partition Assistant Pro.

AOMEI Partition Assistant supports for converting disk from MBR to GPT without losing data because of its powerful function "Convert to GPT".

Once you click “Convert to GPT”, there are only four steps remain: “OK” →“ Yes” →“ Apply”→ “Proceed”. Every step has a hint message. You can refer to this article: “The Simplest Way to Convert MBR Partition Table to GPT”. With the clear prompts, the operations of conversion can be completed easily and securely. Therefore, I recommend the second solution.

If you want to learn more features of AOMEI Partition Assistant. Please click here. The newest version of AOMEI Partition Assistant has an amazing function named “Windows to Go Creator”, which helps you build a portable Windows 8 workspace.