The short answer: choose GPT for your drive. It is the newer standard and has plenty of advantages over the aging MBR. Still, I'll go a bit deeper here so you get a clearer overall picture of what MBR and GPT are, and how they differ when it comes to hard drives and operating systems.
MBR and GPT
MBR, or Master Boot Record, is a special boot sector at the very start of the partitions on a storage device (drive) used in a computer. It is the default partition table format and has been in use for a very long time (since 1983, on PCs running DOS 2.0). MBR holds information on how the logical partitions containing the file system are organized. It also contains executable code that acts as a loader for the installed operating system, either by passing control to the second stage of the loader or by working together with the VBR (volume boot record) of each partition. The MBR code is also called the boot loader.
Only storage devices that can be partitioned have an MBR, while devices such as floppy disks do not. Because of its 32-bit limit, the maximum size of the partition table in MBR is 2 TB (more precisely, 2^32 x 512 bytes per sector), with up to 4 primary partitions at a time. So if a drive exceeds that limit and uses MBR, only 2 TB of its space can be used. That is why, in the late 1990s, Intel developed a new partition table format, GPT (which later became part of the UEFI standard, the Unified Extensible Firmware Interface), to address the ever faster growth in hard drive capacity.
GPT is an acronym that contains another acronym: the G stands for GUID (Globally Unique Identifier) and PT stands for Partition Table. GPT uses 64 bits for the logical block address, so on a drive with 512-byte sectors, the maximum capacity GPT can recognize is more than 8.5 billion TiB (2^64 x 512), or 9.44 ZB. In 2010, hard drive makers introduced Advanced Format, with 4096 bytes per sector, so for this type of drive the maximum capacity GPT can handle is 2^64 x 4096, or roughly 68.72 billion TiB, or 75.56 ZB. For compatibility with older hardware and software, Advanced Format drives include 512e emulation technology, which lets the system see the physical 4096-byte sectors as the familiar 512-byte sectors when accessing the drive.
Drive Partitions
Every storage device today needs at least 1 partition before it can work, much like owning a plot of land that hasn't been assigned a purpose: you can't farm it or build a house on it. Even if you have a single physical drive, it can hold multiple logical partitions. MBR's limit of 4 primary partitions can be worked around with logical partitions: you create 3 primary partitions and 1 extended partition, and inside the extended partition you can create additional logical partitions.
However, only primary partitions can be used to boot an operating system (they hold the system files); logical partitions cannot. Having several primary partitions serves the need to boot multiple operating systems. For example, you might want Windows 10, Windows 7 and Windows XP on the same drive and choose which one to boot into for different purposes.
GPT also limits the number of primary partitions, but on Windows that limit is far higher, 32 times that of MBR. That means you can freely create up to 128 primary partitions on the same drive without any problems. Other operating systems even allow more primary partitions than that, but I don't think ordinary users need anywhere near that many.
Drive Capacity and Compatibility
As mentioned above, the capacity limit MBR can recognize is 2 TB, while GPT goes up to 9.44 ZB (more precisely, 9,444,732,965 TB). That makes GPT better suited to new drives today, when even SSDs have capacities beyond the MBR limit. That said, choosing between MBR and GPT also depends on your hardware and your operating system. Every Windows version up to and including Windows 10 supports MBR, and among them Vista, 7, 8 and 10 also support GPT, while Windows 11 uses GPT only. So if you are installing Windows XP, for example, you have to use MBR. In addition, a GPT partition can only boot on a mainboard that uses UEFI, so if your hardware is very old and uses BIOS, MBR is your only option. If the drive is used purely for storage and doesn't boot, it doesn't matter whether it is GPT or MBR.
Nearly all new computer systems in recent years use UEFI instead of BIOS, so you can feel confident about compatibility when using GPT. If you still cling to operating systems from Windows XP and earlier (2000, Me, 98, 95...), the boot partition format must be MBR. Conversely, GPT support covers systems from Vista onward:
- To boot from a GPT partition, the 64-bit versions of Windows 11, 10, 8/8.1, 7 and Vista, and the 32-bit versions of Windows 10 and 8/8.1, require a UEFI system.
- The 32-bit versions of Windows 7 and Vista do not support booting from a GPT partition and must use MBR.
- All of the operating system versions above can read and write data on a GPT partition normally.
Recoverability
An operating system will sometimes hit errors during startup, and you may need to recover the drive's data. This also relates to MBR and GPT. MBR stores all partition and boot data in one place, so if the data gets corrupted, it is much harder to recover. GPT, on the other hand, stores copies of the boot data across multiple partitions at the beginning and end of the table header, so when one partition is damaged, GPT can use the others to carry out recovery.
GPT also includes an error-detecting code, CRC (cyclic redundancy check), which lets it scan the partition tables during startup to see whether any problem has occurred. If it detects errors, GPT will try to repair them on its own. MBR has no such feature, and you can only tell something went wrong when the system fails to boot or the drive's partition vanishes one fine day.
