Does anyone have hard numbers explaining the maximum number of Teslas a hard disk drive can tolerate before data will be corrupted.

This forum says "a lot", which isn't super helpful.

This one claims you need magnets that only governments have access to in order to erase data, but I'm concerned with what it takes to corrupt data, not completely erase it.

  • 1
    \$\begingroup\$ There is a big difference between corrupting a spinning disk and corrupting a static disc. When exposed to even a fairly modest magnetic field, eddy currents will be able to magnify the magnetic field in a spinning disc locally easily by an order of magnitude, maybe two. This may even be worsened by the proximity effect. Whereas a static disc will need ridiculous field strengths like Myforwik's answer. \$\endgroup\$
    – user36129
    Mar 12, 2014 at 9:05
  • \$\begingroup\$ @user36129 some smaller drives use glass platters so I guess that would make a large difference. \$\endgroup\$ Mar 12, 2014 at 12:18

1 Answer 1


The field intensity required is about 240,000 A/m to penetrate a typical metal harddisk.

Most industry 'wipers' that deguass drives work at between 280,000 to 800,000 A/m.

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    \$\begingroup\$ Thanks for the info. Where did you get this number from? :) \$\endgroup\$ Dec 12, 2013 at 16:42

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