Definitions of degaussers, descriptions of destroyers - and more

Don’t know your coercivity from your continuous duty? Your Tesla from your tape media? Our glossary will explain these terms and more, to give you a little education in the art of degaussing and hard drive destruction.  We feel the degausser market remains a relatively unknown niche, and we’d like to fix that.


A degausser can be a lot of things, but they’re all to do with removing magnetic fields. You may have heard of a degausser being used to clear up a fuzzy CRT screen or wipe a videotape for re-use, but did you know degaussing was first used by the British fleet to counteract German magnetic naval mines during World War II? The kind of degaussing we do is on computer hard drives. A degausser can be used to erase all the data from a drive, leaving it unreadable and unusable.

Nikola Tesla (1857-1943) American inventor. Photograph, 1915. --- Image by © Bettmann/CORBIS


You may know Tesla as the forward-thinking car/spaceship builder, but did you know it’s named after Nikola Tesla, the father of alternating current and inventor of the Tesla coil? You probably knew that. But we’re not talking about either of those! The “Tesla” is a unit of magnetic induction, equal to 10000 Gauss. Some of our degaussers, like the HD-2XTE, put out 1 Tesla of magnetic energy (plenty to wipe a hard drive). The more powerful TS-1XTE puts out 2 Tesla. For reference, an MRI machine puts out up to 7 Tesla – keep metal objects well clear!


Nikola Tesla may have wowed the world with his fancy Tesla coil and large unit of magnetic measurement, but the real hero is Carl Freidrich Gauss, for whom the Gauss unit is named – and thus, the process of “de-Gaussing”! One unit of Gauss may be only 1/10000th of a Tesla, but it’s no less useful. When talking about degausser output, we usually talk in Gauss units. Did you know that with only 160,000 Gauss, you can levitate a frog? It’s true! Just don’t ask me why anyone would want to.



Coercivity is “the resistance of a magnetic material to changes in magnetization”, but you can think of it as “stubbornness”. In the case of hard drives, it means how difficult it is to remove the magnetism (and thus the data) from the drive. Coercivity is measured in Oersteds (Oe). As a rule of thumb, a degausser needs twice the Gauss level of the Oersteds of a hard drive to completely erase it. A 5000 Oe drive would require a 10000 Gauss (or 1 Tesla) degausser. Hard drives from the last 25 years are around 5000 Oe, but new high-capacity drives may be considerably higher – even as high as 15000 Oe!


A flatbed degausser is a bit like a flatbed scanner; you open up the lid and place a hard drive inside to be degaussed. Flatbed degaussers suffer from a number of problems such as requiring manual input and risk of overheating, and have been superseded by capacitive discharge degaussers like the ones we sell. If you’re thinking about buying a flatbed degausser – don’t. That technology has had its day, and the future is capacitive discharge.

Continuous duty

I mentioned that flatbed degaussers have an overheating problem. The term “continuous duty” means that a degausser is able to run non-stop without needing to cool down. All the degaussers we sell are of the continuous duty type.

Capacitive discharge

A capacitive discharge degausser doesn’t push a constant magnetic field at a hard drive to degauss it. This is an inefficient way to do things, which generates a lot of heat. Instead, this type of degausser takes some time to “charge” – in earlier models this was a minute or more, but now it’s just a few seconds – then instantly discharges into the hard drive, like an electromagnetic pulse. Not like the kind you see in sci-fi movies that knocks out power to an entire city – just enough to wipe a hard drive.

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