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Hash Verification Calculator

Work out how long hashing an evidence set takes from algorithm throughput, core count, storage read rate and per-file overhead.

About Hash Verification Calculator

Hashing is a streaming workload, so the time is the data volume divided by whichever ceiling is lower: the CPU's aggregate hash rate, or the rate the storage can deliver bytes. Millions of small files add a fixed cost per file — roughly 1.5 ms for the open, stat and close — which on a 250,000-file set is measured in minutes regardless of throughput. Verification is the step that makes evidence admissible, and it is routinely left out of acquisition schedules until it doubles the elapsed time of a job.

Formula

Hash Verification

hashTime = dataVolume ÷ min(perCoreThroughput × cores × scalingEfficiency, storageReadRate) + fileCount × 1.5 ms of per-file open, stat and close overhead.

perCoreThroughput
GB/s for one core of the chosen algorithm
scalingEfficiency
Fraction of linear speed-up achieved across cores
storageReadRate
Sequential read rate of the evidence store

Worked example

With the default values below, Hash Verification Calculator returns Total Hashing Time of 21.8. Change any input above and every figure here is recalculated in your browser.

Inputs used

Data to hashaccepts 0.1–500,000 GB
500 GB
Algorithm throughput per coreone of SHA-256 with SHA-NI — 1.8 GB/s, SHA-256 software only — 0.55 GB/s, SHA-512 on 64-bit — 0.9 GB/s, SHA-1 — 1.1 GB/s, MD5 — 0.7 GB/s, BLAKE3 single thread — 3.2 GB/s
SHA-256 with SHA-NI — 1.8 GB/s
Cores used for hashingaccepts 1–256 cores
4 cores
Parallel scaling efficiencyaccepts 10–100 %
75 %
Storage read rateaccepts 1–20,000 MB/s
550 MB/s
Number of filesaccepts 1–500,000,000 files
250,000 files
Compute a second algorithm as well
No

Results

Total Hashing Time
21.8 minutes
Effective Hash Throughput
0.54 GB/s
CPU Hashing Ceiling
5.40 GB/s
Storage Read Ceiling
0.54 GB/s
Per-File Overhead
6.3 minutes
Limiting Factor
Storage read rate — the disks cannot feed the CPUs

Step by step

  1. 1Values used
  2. 2Hash Verification
  3. 3Total Hashing Time= 21.8 minutes
  4. 4Effective Hash Throughput= 0.54 GB/s
  5. 5CPU Hashing Ceiling= 5.40 GB/s
  6. 6Storage Read Ceiling= 0.54 GB/s
  7. 7Per-File Overhead= 6.3 minutes
  8. 8Limiting Factor= Storage read rate — the disks cannot feed the CPUs

Assumptions and limits

  • The result is derived only from the 7 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

How is Hash Verification calculated?

hashTime = dataVolume ÷ min(perCoreThroughput × cores × scalingEfficiency, storageReadRate) + fileCount × 1.5 ms of per-file open, stat and close overhead. Hashing is a streaming workload, so the time is the data volume divided by whichever ceiling is lower: the CPU's aggregate hash rate, or the rate the storage can deliver bytes. Millions of small files add a fixed cost per file — roughly 1.5 ms for the open, stat and close — which on a 250,000-file set is measured in minutes regardless of throughput.

Why does Hash Verification matter?

Verification is the step that makes evidence admissible, and it is routinely left out of acquisition schedules until it doubles the elapsed time of a job.

What values do I need to enter?

This calculator takes 7 inputs: Data to hash, Algorithm throughput per core, Cores used for hashing, Parallel scaling efficiency, Storage read rate, Number of files, Compute a second algorithm as well. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

Is MD5 still acceptable for evidence integrity?

For integrity against accidental corruption, yes, and many tools still record it. For anything an opponent might contest, use SHA-256: MD5 and SHA-1 have practical collision attacks, so a defence expert can argue that two different files could carry the same digest.

Why is dual hashing less than twice the cost?

Because the read is shared. Both digests are computed over the same buffered stream, so you pay the I/O once and only the CPU work doubles — in practice about 1.8× the single-algorithm time.

Related Calculators

Hash Verification Calculator – Calculate Total Hashing Time