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Data Wipe Passes Calculator

Work out data wipe passes instantly with clear inputs, formula shown and shareable results.

About Data Wipe Passes Calculator

NIST SP 800-88 replaced pass-count folklore with three categories: clear, purge and destroy. A single overwrite pass is sufficient to clear a modern magnetic disk; SSDs need the controller's own sanitise command because overwriting cannot reach over-provisioned blocks; and self-encrypting drives are purged instantly by destroying the media encryption key. Multi-pass schemes such as the old DoD 5220.22-M pattern are obsolete.

Formula

Sanitisation decision

magnetic disk: 1 pass overwrite; SSD or SED: cryptographic erase or controller sanitise; time = capacity x passes / write speed

Worked example

With the default values below, Data Wipe Passes Calculator returns Overwrite passes required of 0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Media typeone of Magnetic hard disk, Solid state drive, Self-encrypting drive, Magnetic tape
Solid state drive
Data sensitivityone of Low - internal use, Medium - confidential, High - restricted or regulated
High - restricted or regulated
Capacity per unitminimum 1 GB
1,000 GB
Write speedminimum 1 MB/s
200 MB/s

Results

Overwrite passes required
0
Recommended sanitisation method
ATA sanitise / NVMe format with secure erase - overwriting cannot reach spare blocks
Estimated time per unit
5 s
Verification requirement
Yes - verify a sample of blocks and retain a certificate of sanitisation

Step by step

  1. 1Values used
  2. 2Sanitisation decision
  3. 3Overwrite passes required= 0
  4. 4Recommended sanitisation method= ATA sanitise / NVMe format with secure erase - overwriting cannot reach spare blocks
  5. 5Estimated time per unit= 5 s
  6. 6Verification requirement= Yes - verify a sample of blocks and retain a certificate of sanitisation

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 whole numbers, 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 the 35-pass Gutmann method ever needed?

No. It targeted encoding schemes used by 1990s drives and has no relevance to modern media. It wastes days of drive time for no security benefit.

When is physical destruction required?

When the media has failed and cannot accept sanitisation commands, or when policy for restricted data mandates destroy rather than purge. Shredding to a specified particle size is the usual standard.

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