How Do I Fully Use 4 TB or 3 TB Capacity on MBR with 2 Partitions?

In the following article, I will describe how to use 4 TB or 3 TB on the MBR with two partitions in Windows 10, 8, and 7. If you are facing confusion, you can figure it out here.


By Dervish / Updated on May 12, 2023

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Can I use 2 partitions on 3 TB MBR HDD?


I am facing such a problem. I used 3 TB capacity on the MBR, but in fact, the capacity I can use is only 2 TB. Now, I want to keep the MBR partition style unchanged, but also want to use up the other 1 TB capacity and create a new partition with the unallocated space. 3 TB MBR can’t create two partitions?, if I want to use the 3 TB capacity on the MBR with two partitions, is there any way to help me achieve this goal?"


You need to convert 4 TB/3 TB MBR to GPT before creating two partitions

If you want to make full use of a 3 TB or 4 TB MBR hard drive, you need toconvert the MBR partition styleto GPT. Because MBR only supports a maximum partition size of 2 TB, and only four primary partitions can be created, while GPT disks can support the creation of more partitions with larger capacity without practical limitations. Therefore, it is not that 3 TB/ 4 TB MBR can't create two partitions, but MBR cannot create partitions larger than 2 TB.

So, what exactly are MBR and GPT? MBR (Master Boot Record) and GPT (GUID Partition Table) are two commonly used partition tables in Windows systems. The partition table is a table used to describe the partitions on the HDD or SSD and help the drive locate files so that the operating system can read the data on the drive.

But the difference is that MBR needs to use BIOS to boot, while GPT needs to use UEFI to boot. GPT has more advantages than MBR. Because GPT disks have stronger error resistance and higher security. The specific differences are shown in the following figure:

Two ways to convert 4 TB/3 TB MBR to GPT in Windows

There aretwo options to convert MBR to GPT. One is a Windows built-in tool, and the other is a third-party conversion software. I will demonstrate for you one by one.

Way 1. Convert 4 TB/3 TB drive to GPT with Diskpart (data loss)

Diskpart can convert MBR to GPT with several lines of command. Here are the detailed steps.

1. This method needs to clean your disk before converting, so if it is not a new hard drive or has important data on it, you have to back up the disk in advance.
2. Generally, MBR and BIOS (MBR+BIOS), GPT and UEFI (GPT+UEFI) are complementary to each other. When converting the system disk to GPT disk, please make sure that your computer motherboard supports UEFI boot mode.

Step 1. Press “WIN+R”, type “CMD” and press Enter to open the Command Prompt. Then, input "diskpart" and hit Enter.

Step 2. Type the following commands, remember to press Enter after you input each one.

● list disk
● select disk 1 (number means the drive letter, replace it with your 4 TB drive letter)
● clean (clear all partitions on the selected disk)

● convert GPT

When the “DiskPart successfully converted the selected disk to GPT format” shows on the screen, type “exit” and press “Enter” to leave the program. At this time, your partition style has been converted from MBR to GPT and the capacity has been extended.

 Way 2. Convert 4 TB/3 TB drive to GPT via third-partysoftware (data safe) 

Diskpart Command Line is an effective way to convert MBR to GPT, but it has an obvious disadvantage: you have to delete all existing partitions and data on the drive. Moreover, these command lines may be difficult to remember in a short time for users without computer background. And it is easy to input the wrong disk number and lose important files.

Therefore, you can turn to the free and powerful partition software--AOMEI Partition Assistant Standard(compatible with Windows 11/10/8/7). It can convert 4 TB/3 TB MBR disks into GPT disks without losing any data.

AOMEI Partition Assistant Standard can convert the data disk from MBR/GPT to GPT/MBR. If you want to convert the system disk from MBR to GPT, you need to upgrade to Professional Edition. In addition, it can also Migrate OS from GPT disk to GPT/MBR disk, realize the conversion between FAT32 and exFAT, etc.

Download Freeware Win 11/10/8.1/8/7/XP
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Step 1. Install and launch Partition Assistant Standard. Right-click the hard drive you want to convert and select Convert to GPT.


Step 2. Click OK in the pop-up window to confirm the operation. Now you will find the partitioning scheme has turned into GPT. Don’t forget to click Apply to execute this task.

Step 3. Click Apply after your confirmation.

Now you can see that Disk 2 has been converted into a GPT disk, and you can create new partitions in the unallocated space.

Sum up

In summary, I have used two methods to solve 3 TB/4 TB MBR two partitions for you. If you are familiar with computers, then you can use Diskpart, but if you are a rookie, AOMEI Partition Assistant may be a more suitable choice for you.​

Dervish · Staff Editor
Dervish is an English editor of AOMEI Technology; He is delicated to offering users easy and effecitve solutions for issuses related to disks and partitoins. In his spare time, he enjoy wathcning films, playing footable, traveling and so on.