Software & Apps Windows What Is the Master Partition Table? The MPT stores information about partitions by Tim Fisher General Manager, VP, Lifewire.com Tim Fisher has 30+ years' professional technology support experience. He writes troubleshooting content and is the General Manager of Lifewire. our editorial process Facebook Twitter LinkedIn Tim Fisher Updated on February 14, 2020 Windows The Ultimate Laptop Buying Guide Tweet Share Email The master partition table is a component of the master boot record/sector that contains a description of the partitions on the hard disk drive, like their types and sizes. The master partition table accompanies the disk signature and master boot code to form the master boot record. Due to the size (64 bytes) of the master partition table, a maximum of four partitions (16 bytes each) may be defined on a hard drive. However, additional partitions can be set up by defining one of the physical partitions as an extended partition and then defining additional logical partitions within that extended partition. Photo by Patrick Lindenberg on Unsplash Free disk partitioning tools are an easy way to manipulate partitions, mark partitions as "Active," and more. Other Names for the Master Partition Table The master partition table is sometimes referred to as just partition table or partition map, or even abbreviated as MPT. Master Partition Table Structure and Location The master boot record includes 446 bytes of code, followed by the partition table with 64 bytes, and the remaining two bytes are reserved for the disk signature. Here are the specific duties of each 16 bytes of a master partition table: Size (Bytes) Description 1 This contains the boot label 1 Starting head 1 Starting sector (first six bits) and starting cylinder (higher two bits) 1 This byte holds the lower eight bits of the starting cylinder 1 This contains the partition type 1 Ending head 1 Ending sector (first six bits) and ending cylinder (higher two bits) 1 This byte holds the lower eight bits of the ending cylinder 4 Leading sectors of the partition 4 Number of sectors in the partition The boot label is particularly useful when more than one operating system is installed on the hard drive. Since there is then more than one primary partition, the boot label lets you choose which OS to boot to. However, the partition table always keeps track of one partition that serves as the "Active" one that gets booted to if no other options are chosen. The partition type section of the partition table refers to the file system on that partition, where the 06 or 0E partition ID means FAT, 0B or 0C means FAT32, and 07 means NTFS or OS/2 HPFS. With a partition that's 512 bytes for every sector, you need to multiply the total number of sectors by 512 to get the number of bytes of the total partition. That number can then be divided by 1,024 to get the number into kilobytes, and then again for megabytes, and again for gigabytes, if needed. How Do Bits, Bytes, Megabytes, Megabits, and Gigabits Differ? After the first partition table, which is offset 1BE of the MBR, the other partition tables for the second, third, and fourth primary partition, are at 1CE, 1DE, and 1EE: Offset Offset Hex Decimal Length (Bytes) Description 1BE - 1CD 446-461 16 Primary Partition 1 1CE-1DD 462-477 16 Primary Partition 2 1DE-1ED 478-493 16 Primary Partition 3 1EE-1FD 494-509 16 Primary Partition 4 You can read the hex version of the master partition table with tools like wxHexEditor and Active@ Disk Editor. Was this page helpful? Thanks for letting us know! Get the Latest Tech News Delivered Every Day Email Address Sign up There was an error. Please try again. You're in! Thanks for signing up. There was an error. Please try again. Thank you for signing up. Tell us why! Other Not enough details Hard to understand Submit More from Lifewire What Is a Master Boot Record (MBR)? What Is the Volume Boot Code? The Linux Command — fdisk Apple Partition Types: How and When to Use Them What Is the Master Boot Code? What Is a Boot Sector? How to Deal With Boot Sector Viruses 10 Best Free Disk Partition Software Tools EaseUS Partition Master Free Edition v15 What Are Extended Partitions? What Is a Partition? MiniTool Partition Wizard Free v12.3 What Is a Disk Signature and Why Is It Necessary? How to Install Puppy Linux Tahr on a USB Drive AOMEI Partition Assistant Standard Edition v9.1 What Is a Volume Boot Record?