Secure Erase Time Calculator

Work out secure erase time instantly with clear inputs, formula shown and shareable results.

About Secure Erase Time Calculator

Overwrite time is capacity times passes divided by sustained write speed, which makes multi-pass erasure of large drives take many hours each. Cryptographic erase destroys the drive's internal encryption key instead and completes in seconds, which is why NIST SP 800-88 treats it as the preferred method for self-encrypting drives and for SSDs, where overwriting cannot reach over-provisioned blocks anyway.

Formula

Erase time

per drive = capacity x passes / write speed (cryptographic erase is near instant); total = per drive x drives

Worked example

With the default values below, Secure Erase Time Calculator returns Total erasure time of 533,333. Change any input above and every figure here is recalculated in your browser.

Inputs used

Drive capacityminimum 1 GB: 4,000 GB
Sustained write speedminimum 1 MB/s: 180 MB/s
Erase methodone of Cryptographic erase (key destruction), Single-pass overwrite, Three-pass overwrite, Seven-pass overwrite: Single-pass overwrite
Drives to eraseminimum 1: 24

Results

Total erasure time: 533,333 s
Time per drive: 22,222 s
Total time in hours: 148.15 h
Overwrite passes: 1

Step by step

1Values used
2Erase time
3Total erasure time= 533,333 s
4Time per drive= 22,222 s
5Total time in hours= 148.15 h
6Overwrite passes= 1

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Is a single pass enough?

For magnetic drives, yes. NIST SP 800-88 states a single overwrite pass renders data unrecoverable on modern drives; the old multi-pass folklore predates current areal densities.

Why does overwriting fail on SSDs?

Wear levelling and over-provisioning mean the controller may not expose every physical block. Use the drive's sanitise or cryptographic erase command instead.