Degaussing for Data Erasure: What It Is, Why It Matters, How It Works

What is degaussing?

Degaussing is a media sanitisation technique that exposes magnetic storage to a strong magnetic field, randomising and neutralising magnetic domains so that data is unrecoverable. In simple terms, degaussing means wiping data from magnetic media by exposing it to a powerful magnetic field that completely erases everything stored on it.

In NIST SP 800‑88, degaussing is one of the purge techniques for certain media types; the 2025 draft revision continues to frame sanitisation as rendering access to data “infeasible” for a given level of effort. The UK NCSC adds an operational note: degaussing can be used to sanitise exclusively magnetic media, but not all degaussers work on all HDD technologies, so field strength and media coercivity matter.

When should you use degaussing?

Use degaussing when you need rapid, forensically sound sanitisation of magnetic HDDs or magnetic tapes that are not intended for reuse (or where reuse of the specific media type is impossible post‑degauss, for example, LTO). For higher assurance programs (defence, government, or critical sectors), NSA 2025 guidance calls for degauss plus physical platter deformation for HDDs to complete sanitisation.

Do not choose degaussing for SSDs, flash or optical media; there’s no magnetic recording to neutralise. The seminal UCSD study also shows traditional magnetic-oriented erasure methods don’t map to flash; use device‑specific sanitise and secure erase or destruction.

How degaussing works (and types of degaussers)

The physics in brief

Magnetic media resist changes to their recorded state according to coercivity, measured in Oersteds (Oe). To erase reliably, the degausser’s applied field must meet or exceed the medium’s coercivity; industry practice often targets ~1.5×–2× the media’s Oe rating. The NSA 2025 EPL warns that due to modern HDD advances, they no longer accept degaussers <30,000 gauss for evaluation, and they list HDD ratings up to L‑5000/P‑5000 Oe. (Source: National Security Agency)

(Rule‑of‑thumb multiples are common in vendor engineering notes; always anchor device selection to NSA/NCSC/NIST guidance and the specific media’s Oe.)

Types of Degaussing technologies you’ll see:

• Capacitive discharge (“pulse”) degaussers: Energy stored in capacitors is released in a brief, intense pulse through a coil. Preferred for modern HDDs because they can deliver very high peak fields without overheating.
• Continuous/AC “coil” degaussers: Generate a continuous alternating field; commonly used for many tape formats, but can have duty‑cycle/heat limits.
• Permanent‑magnet degaussers: Use rare‑earth magnets for high field strength; often integrated into high‑throughput conveyor systems.
• Verification matters: NSA lists approved field verification devices and requires post‑degauss HDD platter deformation as part of the sanitisation chain.

Will degaussing work on my media? (compatibility matrix)

Standards and compliance mapping

NIST SP 800‑88 Rev.1 & r2 (ipd 2025): Defines Clear / Purge / Destroy; degaussing is a purge technique for suitable magnetic media; stresses validation and programmatic controls in r2 draft.

NSA/CSS EPLs (July and Jan 2025):

• Magnetic degaussers: ≥30,000 gauss accepted for evaluation; match device to media Oe (HDD up to L‑5000/P‑5000 Oe).
• HDD destruction devices: Degauss + platter deformation required for routine HDD sanitisation; 2 mm particle size qualifies shredding as sanitisation in specific emergency contexts.

UK NCSC (Reviewed Feb 2025): For OFFICIAL data, outlines reuse/disposal flows; degauss for exclusively magnetic media; for destruction, ≤6 mm particles can be required depending on risk; emphasises verification.

ISO/IEC 27040:2024 (Storage security): Provides current storage security concepts/controls, including references to sanitisation practices across storage architectures.

IEEE 2883:2022 (Sanitising storage): Modern, device‑centric guidance for logical and physical sanitisation across media (includes Clear/Purge/Destruct alignment).

ISO/IEC 21964 / DIN 66399 (Destruction): International framework for particle sizes/protection classes when physically destroying data carriers.

GDPR / Storage limitation (Art. 5(1)(e)): Requires organisations to delete personal data when no longer necessary, and sanitisation supports this control.

WEEE Directive (2012/19/EU): Obligations for responsible treatment/recycling of end‑of‑life electronics post-sanitisation.

Pros, cons and environmental notes

Benefits

• Speed and certainty on magnetic media; degaussing obliterates all tracks and hidden areas in one pass (when using properly rated equipment).
• Air‑gapped: offline, not susceptible to firmware trickery or interface constraints. (NIST categorises it as purge for appropriate media.)

Limitations

• Media reuse: HDDs and LTO are typically unusable post‑degauss because servo information is erased. This can reduce circularity unless parts are recycled.
• Not for SSD: no effect; must use logical sanitise or destruction.

Sustainability

• Circular IT group prioritises reuse where safe and possible (e.g., Blancco erasure for HDD and SSD when reuse is intended). Degaussing is reserved for non‑reusable magnetic media or high‑assurance decommissioning, with WEEE‑compliant recycling downstream.

How Circular IT group implements degaussing

1. Scope and classify media against your risk profile (NIST/ISO27040).
2. Select an NSA‑listed degausser matched to media Oe; validate field strength with an NSA‑approved verifier.
   Operate on‑site or in chain‑of‑custody facilities with auditable logs.
3. Follow with physical deformation of HDD platters (shredder) to complete the NSA workflow.
4. Issue evidence: serial‑level logs, videos and photos on request, and a certificate of sanitisation with method and device IDs.
5. Recycle responsibly under WEEE; provide materials recovery reporting

How degaussing compares to other options

Circular IT group’s data erasure process

When you need a partner to erase, destroy, remove, and report, end-to-end, Circular IT group delivers a full ITAD stack built for security, compliance, and circular outcomes. Services span certified software data erasure, physical destruction and shredding both on‑site and off‑site, and turnkey data centre decommissioning, all backed by auditable reporting and recognised certifications.

What we deliver:

• Certified data erasure (software)

  Devices are wiped with Blancco to international standards, keeping assets reusable and circular. Coverage includes HDDs, SSDs and mobiles; service is available on‑site or via secure collection to our service centres, with certificates issued for every job.

  Data erasure

• Physical destruction and shredding

  For media that must be rendered unusable, we shred on‑site (mobile shredder at your premises) or off‑site. You receive a detailed destruction certificate with timestamps and unique item identifiers; shredded fractions are routed to WEEELABEX‑certified recycling partners.

  Data destruction

• Solid‑state (SSD) destruction

  Shredding meets DIN 66399 E5/H5 with processes aligned to NIST 800‑88, ISO 27001 and NEN 7510, and includes secure, tracked transport across Europe when performed off‑site.

  SSD destruction

• Data‑centre decommissioning

  A complete, auditable package: on‑site wiping and shredding, secure transport, certified processing and recycling, plus transparent, audit‑ready reporting throughout the pipeline.

  Data‑centre decommissioning

• Asset recovery and remarketing

  Integrate erasure and destruction with valuation, resale or redeployment. All supported by real‑time tracking and comprehensive reporting.

  It asset recovery

Blog sources

NIST SP 800‑88 Rev.1 and Rev.2 (ipd, 2025)—media sanitisation program & methods.

NSA/CSS 2025 EPLs—Magnetic degaussers (≥30,000 gauss; Oe mapping); HDD destruction devices (degauss + deformation; 2 mm note).

NCSC (UK) 2025—Secure sanitisation & disposal; degauss for exclusively magnetic media; destruction particle guidance.

ISO/IEC 27040:2024—storage security guidance.

IEEE 2883:2022—sanitising storage (Clear/Purge/Destruct).

Fujifilm tape note—degaussing LTO erases servo → unusable.

UCSD FAST’11 (Wei et al.)—SSDs require different sanitisation methods; degaussing has no effect.