What does degaussing do to a hard drive?

Degaussing is a process that reduces or eliminates the magnetism from an object or magnetic storage media. According to Wikipedia, degaussing works by applying an alternating magnetic field to an object, gradually reducing the magnetic field to zero. The term originated from a device known as a “degausseur” that was patented in 1884 by Charles Eugene Lancelot Brown to demagnetize the steel hulls of ships.

Degaussing became commonly used in the computing industry in the 1950s to erase data from magnetic storage like hard disk drives and tapes. It works by randomizing the magnetic domains on the drive platter, effectively removing any previously stored data. When applied to a hard drive, degaussing renders all the data unreadable by eliminating the magnetic signature holding the encoded bits. The process essentially demagnetizes the entire drive surface.

Compared to simply deleting files or reformatting a drive, degaussing is a more effective data sanitization method that helps prevent recovery of erased data. However, degaussing renders the drive permanently unusable. The process damages the platters and drive components through strong magnetic forces, making the hard drive unusable.

How Degaussing Works

Degaussing works by exposing magnetic storage media, like hard drives, to an alternating magnetic field. This field randomizes the orientation of magnetic domains on the drive’s platter surface, effectively erasing any previously stored data (Ontrack).

Specifically, degaussing machines generate a strong alternating magnetic field using electromagnets. As this alternating field is applied to a hard drive, it randomizes the magnetic orientation of each bit, disrupting the previously organized pattern that comprised the drive’s data. This renders the original data unreadable and overwritten (Shredstation).

The powerful alternating electromagnetic currents inside a degausser are able to penetrate casing and coatings to reach the internal platters. This allows degaussing to completly scramble the magnetic domains to erase data, without requiring the drive to be opened or removed from the computer (Ontrack).

Effect on Hard Drives

Degaussing has a significant impact on hard drives. It randomizes all of the data stored on the drive by exposing it to a powerful, alternating magnetic field. This essentially scrambles the magnetic orientation of the bits on the drive platters into a completely random pattern.

Once a hard drive has been degaussed, the data is rendered unrecoverable. Even using advanced forensic data recovery techniques, it is virtually impossible to reconstruct the original data after degaussing. This is because the process essentially destroys the underlying magnetic structure that the data was recorded onto.

Degaussing is considered more thorough and secure than simply formatting or deleting files on a hard drive. Formatting only removes the file system structure and does not touch the actual contents of the drive. Degaussing physically randomizes the magnetic fields, making recovery impossible. This is why degaussing is recommended for permanently destroying sensitive data on hard drives.

According to Drivesavers, “Data stored on a degaussed drive is irrevocably destroyed and has no hope of return or recovery.” (https://drivesaversdatarecovery.com/everything-you-need-to-know-about-hard-drive-degaussing/)

Advantages of Degaussing

There are several key advantages to using degaussing to erase data from hard drives:

Degaussing is one of the most secure methods for data destruction. According to Mediaduplicationsystems.com, “Degaussing a hard drive is the most secure way to erase data as it permanently destroys all data on the drive by randomizing the magnetic fields on the disk” (source). This makes retrieving or reconstructing data from a degaussed drive practically impossible.

The degaussing process is also much more environmentally friendly compared to physically destroying hard drives. As noted by AOZhouClick, “degaussing allows organizations to reuse, recycle, sell or donate hard drives after erasing them” (source). It is a non-destructive method.

Finally, degaussing can be a relatively quick process taking just seconds or minutes to completely erase data from a hard drive. The entire degaussing procedure is automated and efficient compared to manual data destruction techniques.

Limitations of Degaussing

While degaussing can be an effective method for sanitizing traditional hard disk drives, the technology does have some limitations to be aware of:

Degaussing may not fully erase data from solid-state drives (SSDs). SSDs store data in flash memory chips rather than on magnetic platters like traditional hard drives. The electromagnetic degaussing fields can disrupt but not completely erase the data stored on SSDs (https://datarecovery.com/rd/what-is-hard-drive-degaussing/).

Degaussing cannot target and erase specific data or files. The process simply eliminates all data stored on the drive by disrupting the magnetic field. You cannot selectively degauss certain files or directories (https://www.bitraser.com/article/data-destruction-techniques.php).

Specialized and expensive degaussing equipment is required. Degaussing machines generate powerful magnetic fields and are not standard IT equipment. Purchasing degaussing hardware represents a significant upfront investment (https://www.bitraser.com/article/data-destruction-techniques.php).

Degaussing vs Other Methods

Degaussing differs from other common data destruction methods like formatting and physical destruction in some key ways:

Compared to formatting, degaussing more completely removes data from a hard drive. Formatting simply removes address tables and pointers to data, but does not erase the data itself. Degaussing magnetically erases data from the drive platters at a low level to make recovery very difficult, if not impossible. This source provides more details on the differences.

Unlike physical destruction through shredding or crushing, degaussing allows the hard drive hardware to be reused after data erasure. So degaussing is preferable when the goal is to securely wipe sensitive data but also recover value from the hardware.

Degaussing is best suited for quickly erasing large volumes of data and hard drives. It’s preferable over other methods when reusable hardware and fast, secure data destruction are top priorities.

Standards and Regulations

There are standards and regulations regarding the degaussing of hard drives, especially when handling sensitive or classified data. Government agencies such as the Department of Defense (DoD) and National Security Agency (NSA) have established requirements for proper degaussing methods and equipment. Some key standards include:

The NSA Information Systems Security Organization has specified the NSA/CSS Evaluated Products List for High Security Crosscut Paper Disintegrators as NSA/CSS Specification 02-01 for degaussing and destroying paper documents (1).

DoD standard 5220.22-M provides requirements for clearing, sanitizing and destroying data storage devices including degaussing. Degaussers must meet a minimum level of 10,000 Gauss (2).

NIST Special Publication 800-36 provides guidelines on data sanitization including degaussing and specifies field strengths needed to sanitize various media (3).

To comply with these standards, organizations must utilize degaussers that are NSA-approved and meet the minimum Gauss rating. Using certified equipment from reputable vendors ensures proper sanitization and compliance with regulations like HIPAA, GDPR, and others requiring secure data destruction. Proper degaussing documentation should be maintained as evidence of due diligence.


(1) https://www.veritysystems.com/resources/faqs/

(2) https://irp.fas.org/nsa/rainbow/tg025-2.htm

(3) https://agtech.hk/degausser-faq-4/

When to Use Degaussing

Degaussing is most commonly used for secure data destruction when recycling or disposing of old hard drives. It provides a way to completely erase confidential data so it cannot be recovered. According to Verity Systems, degaussing is the most secure method for erasing hard drives. It is an ideal solution when you need to protect sensitive information before getting rid of a hard drive.

Specifically, you may want to degauss hard drives when:

  • Permanently erasing data from old hard drives before disposal
  • Sanitizing drives as part of an IT asset disposition or e-waste recycling program
  • Removing confidential data prior to selling or donating used hard drives
  • Destroying sensitive information from drives that are no longer needed
  • Wiping data from hard drives of decommissioned computers and servers

Degaussing ensures data cannot be recovered from the drive even using advanced forensic methods. It provides a high level of security when permanently destroying data. This makes it an ideal choice over simply formatting or deleting files when faced with securely wiping confidential hard drive contents.

Degaussing Process Step-by-Step

To properly degauss a hard drive, you should take the following steps:

1. Prepare the hard drive by removing it from any enclosure or external casing. The degaussing field needs to be able to reach the disk platters directly.

2. Only use a certified degaussing tool that complies with industry standards like NSA/CSS EPL-1M (per PartitionWizard). Handheld degaussing wands are not powerful enough for modern high-density drives.

3. Run the degaussing cycle at least 3 times to ensure complete erasure. The high magnetic field will realign the magnetic domains to random patterns.

4. To confirm all data has been destroyed, run a utility like DiskWipe or Darik’s Boot and Nuke (DBAN) on the drive after degaussing. Then, do a full reformatting of the hard drive.

Following this proper procedure will magnetically sanitize the drive and ensures no data can be recovered, even using advanced forensic methods.


In summary, degaussing is an effective method for completely erasing data from hard drives by exposing them to a strong magnetic field. This magnetic field randomizes the orientation of magnetic domains on the drive, rendering previous data unrecoverable. Degaussing has advantages over physical destruction and software erasure, as it is fast, efficient, and meets regulatory standards like HIPAA for safe data destruction.

Looking ahead, degaussing will continue to play an important role in secure data wiping, especially for organizations with large volumes of drives to purge. As storage technologies evolve, degaussers will need to adapt to effectively erase new types of drives. Solid state drives may present challenges in the future, requiring adaptations or alternative erasure methods.

For readers interested in exploring degaussing further, associations like the National Association for Information Destruction provide resources on degausser selection, standards compliance, and best practices. Manufacturers also offer detailed product information to help organizations choose the right degaussing equipment to meet their data security needs.