What Is MBR Maximum Size [Full & Quick Guide]

Sherly updated on Jan 11, 2024 | Home >Computer Instruction

If your hard drives are already using the MBR partition or you are considering converting your hard drives to MBR, there are a few things you should know first.

This article tells you everything there is to know about MBR, its maximum size, and more. Continue reading!

What Is the MBR Maximum Size

Master Boot Record, also known as MBR, is a partition type that uses standard BIOS partition tables to store data on a hard drive or an SSD. The MBR partition supports drives that are up to 2 TB.

If your drive is larger than 2 TB, for example, 3 TB, only the first 2 TB will be accessible. The remaining portion of the drive will be shown as "Unallocated."

You can click the following links to learn more about this issue:

Also, an MBR disk can be divided into four primary partitions, i.e., three primary partitions with one extended partition.

And if you are wondering why MBR supports only 2 TB, it is because a hard disk uses 512-byte sectors.

The number of addressing bits in the MBR determines how large a disk can be. MBR addresses storage with 32 bits. As a result, the hard disk's address range is 2^32 = 4G. And since the sector of the drive is 512 bytes, the capacity of the MBR disk is calculated as 4G * 512 bytes = 2 TB.

To tackle MBR's limitations, GPT was introduced. Unlike the MBR, the GPT disk doesn't have such limitations and is used by both Microsoft and Apple.

MBR Maximum Size VS GPT 

So GPT's maximum disk size is 9400000000 TB, whereas MBR's maximum disk size is 2 TB. MBR has 4 partitions, and GPT has 128 partition support. There are a lot of other differences as well.

IBM introduced MBR in 1983 to support the 10 MB hard disk of their then-brand-new IBM Personal Computer XT. On the other hand, GPT was introduced by Intel.

Because GPT is technically superior to MBR, and because Intel has been the default chip manufacturer for both Apple and Microsoft for many years, both Apple and Microsoft use GPT partitioning on their disks.

So, if your hard disk or SSD uses an MBR partition style and you want to convert it to GPT, read our next section to know how to do that. Before skipping to the next section, check the table for the differences between MBR and GPT.

Comparison MBR GPT
Maximum Primary Partitions


Maximum Capacity


9.7 billion terabytes

Boot data location

At the start of the drive

Whole drive

BIOS type

Legacy BIOS


If you want to learn more about the difference between the MBR disk and GPT disk, there is a link for you:

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MBR VS GPT | What's the Difference and Which Is Better

To decide which partitioning method to apply, you should first have a basic understanding of what MBR or GPT is.

mbr structure

Now, let's learn how to break the limits of MBR disk.

How to Break MBR Maximum Size Limit 

For Windows PCs, you can convert your hard drive or SSD from MBR to GPT partition style with just a few clicks using EaseUS Partition Master Professional. This very easy-to-use program makes your life easy by taking care of all your disk-related needs with just a few clicks.

Free Download 

Windows 11/10/8/7100% Secure

With EaseUS Partition Master, you can create or delete partitions based on various file system types, merge or extend partitions, copy OS and your files to other drives, resize, format, or wipe unallocated space, and so much more.

Here are a few other amazing features of EaseUS Partition Master:

If you are someone who has been on the lookout for a tool that unlocks the potential of your drive and grants you control over it, EaseUS Partition Master should be your default choice.

Free Download 

Windows 11/10/8/7100% Secure


To put it simply, MBR is a partition type from the past with many limitations that make it unsuitable for modern use. Fortunately, you can convert the partition type from MBR to GPT, but it can be a bit difficult to do with the traditional tools that are available from Microsoft.

That is why we suggest you use EaseUS Partition Master to convert MBR to GPT in a few seconds.

FAQs About MBR Maximum Size

Here are answers to a few questions that we think will help clear up any additional questions about MBRs' maximum size, if you have any.

1. Should SSD be GPT or MBR?

SSDs can be both GPT and MBR, but we recommend you use GPT instead of MBR because of its limitations.

2. Can SSD use MBR?

If the capacity of the SSD is equal to or less than 2 TB, of course, you can use the MBR partition on an SSD.

3. Can I use MBR on a 3TB drive?

You can, but only 2 TB will be the "allocated" space and will be usable. The remaining 1 TB will not be shown in Disk Management and is unusable.

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Updated by Daisy

Daisy is the Senior editor of the writing team for EaseUS. She has been working at EaseUS for over ten years, starting as a technical writer and moving on to being a team leader of the content group. As a professional author for over ten years, she writes a lot to help people overcome their tech troubles.

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Written by Sherly

Sherly joined EaseUS in 2022 and she has always loved writing articles and enjoys the fun they bring. She receives professional training here, focusing on product performance and other relative knowledge. She has written over 200 articles to help people overcome computing issues.

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