What is the purpose of degaussing a hard drive?

Degaussing a hard drive is the process of using a strong magnet to disrupt and randomize the magnetic fields on a hard disk drive. This effectively erases all the data stored on the drive by making it unreadable. There are a few key reasons why someone may want to degauss a hard drive:

To permanently erase sensitive data

One of the main reasons to degauss a hard drive is to permanently erase sensitive or confidential data before disposing of the drive. Unlike standard delete and format operations, degaussing makes data unrecoverable even using advanced forensic data recovery techniques. This is important when dealing with financial records, medical data, classified government documents or any other information that should not fall into the wrong hands.

Many regulations like HIPAA and Sarbanes-Oxley require proper data sanitization before a hard drive can be disposed of or repurposed. Degaussing meets these regulatory requirements for safe, permanent data destruction.

Before selling or donating old hard drives

Organizations and individuals may want to sell or donate old hard drives when upgrading computer equipment. But first they need to wipe sensitive information by degaussing. This protects customer data, financial information, emails and other confidential data that may still reside on the drive.

Degaussing is an efficient way to prepare multiple hard drives for sale or donation, ensuring no valuable data is given away.

To reuse within a secure environment

Some high-security environments require hard drives to be erased and reused internally. Police evidence lockers, government agencies and financial institutions are examples. Degaussing allows fast, effective redeployment of IT assets within the same secure facility.

The degaussing process clears the drive for reuse while permanently eliminating any residual data from previous usage.

Before sending drives for repair or warranty

When hard drives fail and need repair or warranty service, the disk should first be degaussed. This protects sensitive data from leaving an organization’s control.

Hard drive manufacturers typically require degaussing before accepting drives for exchange or repair. Degaussing also speeds the repair and return process by wiping test data and preparing the drive for quick reintegration after service.

For fast, efficient sanitization

Degaussing quickly and efficiently sanitizes an entire hard drive in just a few seconds. This makes it preferable to time-consuming disk wiping and overwriting methods which can take hours to complete.

The speed of degaussing makes it practical to erase large batches of hard drives. And degaussing is effective on all drive types and interfaces including SATA, SAS, SCSI, IDE and SSDs.

How does degaussing work?

Degaussing utilizes strong permanent magnets or electro-magnets that are many times more powerful than a standard refrigerator magnet. This powerful magnetic field is applied directly to the hard drive for a few seconds. It penetrates the drive casing and corrupts data by randomizing the magnetic orientation of every bit on the drive.

With all the bits in random patterns, the data becomes unrecoverable. The degaussing magnetic field must be strong enough to actually realign the magnetic domains on the drive platters and recording heads themselves.

Degaussing magnetic field strength

Professional degaussers generate a flux density between 8,000 and 20,000 gauss. For reference, a standard refrigerator magnet has around 100 gauss. So a degausser produces a magnetic field 80 to 200 times more powerful than a typical magnet.

This very strong alternating magnetic field reliably scrambles data beyond recovery. At the same time it does not physically damage the drive itself so the HDD or SSD can be safely reused or recycled after degaussing.

Types of degaussers

There are two main types of degaussers used to erase hard drives:

  • Handheld wand degaussers – Small handheld devices that are passed over the surface of the drive to be erased. Effective for degaussing small amounts of drives.
  • Automated conveyor degaussers – Large units that can degauss high volumes of drives continuously. Hard drives are placed on a conveyor belt which passes through a powerful degaussing field.

Advantages of degaussing hard drives

Here are some of the key advantages of using degaussing for hard drive sanitization:

  • Permanently erases all data – Degaussing provides the most secure data wipe possible. The randomized magnetic fields make data unrecoverable even with forensic methods.
  • Fast process – It only takes a few seconds to degauss a drive versus hours for software wiping.
  • Minimal training required – Degaussing is easy to operate with no technical expertise required.
  • Works on any hard drive – Compatible with all types of hard drives regardless of size, speed, interface or encryption.
  • built-in automation options – Large degaussers have conveyors and robots to degauss high volumes of drives with no manual intervention.
  • Meets regulatory standards – Degaussing meets data security regulations like PCI DSS, HIPAA, SOX, GDPR and more.
  • Environmentally friendly – The process is harmless to the drive itself so HDDs and SSDs can be safely reused or recycled.

Disadvantages of degaussing

While degaussing has many benefits, there are some potential downsides:

  • High initial cost – Big automated degaussers can be expensive with prices from $3,000 to over $30,000.
  • Manual process for handheld units – Wand degaussers require manually erasing drives one-by-one.
  • Destructive process – Degaussing damages the drive’s servo tracks so it can no longer reliably store data unless reformatted.
  • Not foolproof – Issues like weak magnets, damaged drives, or improper usage can potentially lead to incomplete degaussing.
  • Requires close proximity – The degausser unit or wand must be almost touching the drive for maximum effectiveness.
  • Safety precautions required – Degaussers have extremely strong magnetic fields that can be dangerous if not properly controlled.

Is degaussed data recoverable?

With proper, complete degaussing, all data on the drive will be permanently erased and unrecoverable. However, there are some scenarios where insufficient degaussing could potentially leave some data intact:

  • Weak or underpowered degausser – The magnetic field must be strong enough to fully scramble the drive platters. Using an undersized degausser can leave recoverable remnants.
  • Damaged or non-functioning drive – Drives with physical damage may have areas of platter that are unreachable to the magnetic field, leaving data intact.
  • Incorrect usage – Not holding the degausser in full contact with drive for the proper time interval can result in incomplete erasure.
  • SSDs – Flash memory is generally unaffected by magnetic degaussing, so SSDs require special handling to be securely erased.

With properly trained operators using adequately powered professional degaussers, recovering data from a degaussed hard drive is essentially impossible. But poor procedures or inadequate equipment can potentially leave some recoverable data in limited cases.

Can you degauss an SSD?

Standard magnetic degaussing is ineffective for erasing solid state drives (SSDs). Unlike hard disk drives, SSDs have no magnetic platters or heads. They utilize flash memory chips to store data electronically.

The strong magnetic fields used in degaussing have no impact on the electrical charges within flash memory cells. So alternative methods are required to sanitize data from SSDs:

  • Crypto erase – The SSD controller electronically erases encryption keys, rendering data irretrievable.
  • Block erase – Electronically erases all NAND flash blocks, similar to formatting HDD.
  • Chip erase – Totally clears NAND flash back to factory state.
  • Destroying – Physically destroying the SSD platters and components.

Most SSD manufacturers provide built-in sanitize commands that perform a crypto erase to quickly and effectively scrub data from the drive. This achieves the same end-result as degaussing an HDD.

Can you degauss a flash drive or USB stick?

Like SSDs, USB flash drives use solid state memory so they are not affected by magnetic degaussing fields. However, flash drives do have a couple options for secure data erasure:

  • Format – Perform a full format / overwrite on the drive. Less secure, can leave data remnants.
  • Crypto-erase – Use built-in SSD sanitize commands to cryptographically scrub data.
  • Destroy – Physically dismantle and destroy the chip.

For maximum data security, crypto-erase is recommended over standard formatting. Or physically destroying the device removes any possibility of data recovery.

Can a degaussed hard drive be reused?

Yes, degaussed hard disk drives can safely be reused once reformatted. The powerful magnetic field damages the servo control tracks that precisely position the read/write heads. So the drive can no longer reliably store data until these servo tracks are rebuilt through a full reformat.

Reformatting recreates the servo tracks and file system, making the drive once again a functional blank slate for storing data. The degaussing process causes no physical damage, so the drive hardware remains fully intact.

Many organizations degauss and reformat old HDDs on a regular basis to provide “like-new” internal spares with no residual data traces. Overall it is a very efficient method for securely redeploying storage assets.

Is degaussing necessary with full drive encryption?

With full AES-256 encryption, some argue that degaussing is unnecessary since the data is already cryptographically scrambled. But degaussing provides some important advantages over relying on encryption alone:

  • Permanently erases data – Degaussing provides complete sanitization even if encryption keys somehow become compromised in the future.
  • Faster process – Degaussing takes just seconds versus decrypting and re-encrypting an entire drive.
  • Meets regulatory requirements – Degaussing provides the physical destruction mandated by many data security regulations.
  • No keys to manage – Degaussing avoids any complexity involved with encryption key management.

In high security environments, degaussing offers an extra layer of guaranteed data destruction above and beyond encryption.

Is degaussing enough for secure HDD disposal?

For maximum security, degaussing should be combined with physical destruction as part of a secure hard drive disposal process. Here are some best practices to follow when disposing of degaussed hard drives:

  • Degauss to sanitize – First use degaussing to scramble and erase all data from drive.
  • Destroy platters – Open drive and use a hole punch to shatter platters.
  • Shred remnants – Shred the remains of the drive PCB, casing, etc.
  • Recycle materials – Steel, aluminum, copper can be recycled after destruction.
  • Confirm sanitization – Obtain and file a certificate of degaussing and destruction.

Combining degaussing with physical destruction provides overlapping layers of data security. It ensures no risks from overlooked areas or failed degaussing attempts. The process fully sanitizes drives while enabling recycling.

Compliance with data security regulations

Many regulations and standards relating to data security, privacy and records retention require proper sanitization of storage media like hard disk drives. Degaussing meets the data destruction mandates specified by regulations including:

HIPAA – Healthcare data

The HIPAA privacy rule establishes requirements for protecting personal health information (PHI). Covered entities like hospitals must ensure PHI is unrecoverable from electronic media before disposal.

PCI DSS – Credit card data

PCI DSS requires degaussing, cryptography or physical destruction to render cardholder data unrecoverable on SSDs, HDDs and other media.

SOX – Financial records

Sarbanes-Oxley mandates financial records are properly disposed of through methods like degaussing when no longer needed.

GDPR – Personal data

The EU’s GDPR legislation gives individuals the right to have their personal data securely erased. Degaussing helps organizations comply by thoroughly destroying data.

NIST 800-88 – Digital data sanitization

The NIST guidelines include degaussing as an approved method for purging or destroying digital data from storage devices such as hard drives.

Degaussing provides physical data destruction that satisfies the safe disposal requirements of these and other data security regulations and frameworks.


In summary, degaussing provides a fast, efficient way to permanently erase all data from a hard drive by randomizing magnetic fields. It helps organizations protect confidential data, comply with regulations, and safely repurpose IT assets. When combined with encryption and physical destruction, degaussing serves as an important tool for ensuring complete data sanitization.