We Value Your Privacy

We and our partners use technology such as cookies on our site to personalise content and ads, provide social media features, and analyse our traffic. Click below to consent to the use of this technology across the web. You can change your mind and change your consent choices at anytime by returning to this site.

Update Consent
Loading ...

What is the purpose of formatting a hard drive?

A hard drive is formatted to give it a logical structure that a computer and its operating system will understand. Three operations are generally classified as formatting: low-level formatting, partitioning and high-level formatting. Each of these operations is necessary before the applications that run on a computer can use a hard disk.

Loading ...

Low-level formatting

The low-level formatting process creates the basic logical structure of a hard disk. When disks are produced they are completely blank; low-level formatting gives structure to a disk so that disk controllers can read and write to it properly. A low-level format will divide a disk into tracks and sectors and add information so that disk controllers can locate those tracks and sectors quickly. Low-level formatting completely destroys all data on your hard disk, removing the operating system, applications and any files you had saved. Most hard disks now come with low-level formatting already applied.


Partitioning divides a single physical disk into one or more logical drives. In a Microsoft Windows system, for example, you might partition a disk into a “C” drive and a “D” drive. Even though you only have one physical hard disk in your computer, the Windows operating system treats it as if there were two disks. You can also partition a disk so that one logical drive is used by one operating system and another logical drive is used by another completely different operating system. This is a multi-boot environment where you could choose to boot your computer into Windows or Linux.

High-level formatting

High-level formatting is the process of creating a file system on the disk so that the applications you run on your computer can read from and write to files. File systems are usually operating system-specific and examples of file systems are: FAT and NTFS, used by Windows, and EXT2, EXT3 and EXT4, used by Linux or Unix. Whereas low-level formats operate on the entire disk, high-level formats operate only on logical partitions, so you can high-level format one partition without affecting any other partitions.


High-level formatting a drive overlays a new file system on the old one without removing the old data. Old data is only overwritten when the new file system writes something to a part of the drive that was used by the old file system. With specialist tools, it is still possible to access old data that has not been overwritten. High-level formatting is therefore insecure and if you wish to ensure confidential information is properly overwritten, use either a low-level format or an application that securely overwrites deleted data. Note that high-level formatting a drive will make the old data inaccessible without those specialist tools, so think carefully before performing any sort of format.

Loading ...

About the Author

Gordon Ansell has been an IT specialist since 1981, working for insurance companies, software houses, scientific institutions and television companies. Ansell’s roles have been wide and varied, including systems programmer, software engineer, technical author, systems administrator and project manager. Ansell has written more than 600 posts for one of the most popular Newcastle United blogs.

Loading ...