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Evidence Transfer Time Calculator

Compare shipping evidence over the network against physical courier, including protocol efficiency and hash re-verification.

About Evidence Transfer Time Calculator

A nominal gigabit link rarely delivers a gigabit: TCP windowing over a long fat pipe, encryption and other traffic typically leave 50–70% usable. Both routes end with the same obligation — re-hash on arrival and compare against the acquisition digest — so verification is added to each. The break-even volume is simply how much data the link could have moved during the courier's elapsed time. A courier is embarrassingly fast for large volumes, and 'never underestimate the bandwidth of a van full of disks' is still the right answer above a few terabytes on a shared WAN link.

Formulas

Evidence Transfer Time

networkTime = size × 8 ÷ (bandwidth × usableShare × (1 − encryptionOverhead)); courierTime = preparation + doorToDoor. Both then pay size ÷ hashRate to re-verify on arrival.

usableShare
Fraction of nominal bandwidth TCP actually achieves
encryptionOverhead
Cost of in-transit encryption
doorToDoor
Collection to delivery time for the courier

Break-even volume

breakEvenVolume = effectiveTransferRate × courierElapsedTime — above this volume the courier wins.

effectiveTransferRate
GB per hour actually achieved on the link
courierElapsedTime
Total courier time including packaging

Worked example

With the default values below, Evidence Transfer Time Calculator returns Recommended Method of Network transfer — it lands sooner and keeps custody digital. Change any input above and every figure here is recalculated in your browser.

Inputs used

Evidence to moveaccepts 1–1,000,000 GB
2,000 GB
Link bandwidth availableaccepts 1–400,000 Mbps
1,000 Mbps
Usable share of the linkaccepts 5–100 %
65 %
Encryption overheadaccepts 0–50 %
6 %
Re-verification hash rateaccepts 0.05–10 GB/s
1.2 GB/s
Courier door-to-door timeaccepts 1–720 hours
18 hours
Preparation and packaging timeaccepts 0–72 hours
2 hours

Results

Recommended Method
Network transfer — it lands sooner and keeps custody digital
Network Transfer Time
7.45 hours
Effective Throughput
611 Mbps
Re-verification Time
0.46 hours
Network — End to End
8.41 hours
Courier — End to End
20.46 hours
Break-Even Volume
5,236 GB

Step by step

  1. 1Values used
  2. 2Evidence Transfer Time
  3. 3Break-even volume
  4. 4Recommended Method= Network transfer — it lands sooner and keeps custody digital
  5. 5Network Transfer Time= 7.45 hours
  6. 6Effective Throughput= 611 Mbps
  7. 7Re-verification Time= 0.46 hours
  8. 8Network — End to End= 8.41 hours
  9. 9Courier — End to End= 20.46 hours

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 Evidence Transfer Time calculated?

networkTime = size × 8 ÷ (bandwidth × usableShare × (1 − encryptionOverhead)); courierTime = preparation + doorToDoor. Both then pay size ÷ hashRate to re-verify on arrival. A nominal gigabit link rarely delivers a gigabit: TCP windowing over a long fat pipe, encryption and other traffic typically leave 50–70% usable. Both routes end with the same obligation — re-hash on arrival and compare against the acquisition digest — so verification is added to each. The break-even volume is simply how much data the link could have moved during the courier's elapsed time.

Why does Evidence Transfer Time matter?

A courier is embarrassingly fast for large volumes, and 'never underestimate the bandwidth of a van full of disks' is still the right answer above a few terabytes on a shared WAN link.

What values do I need to enter?

This calculator takes 7 inputs: Evidence to move, Link bandwidth available, Usable share of the link, Encryption overhead, Re-verification hash rate, Courier door-to-door time, Preparation and packaging time. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

Does the courier route need extra controls?

Yes. Physical transfer needs tamper-evident packaging, encryption at rest on the shipped media, a signed custody form at each handover, and a hash comparison on arrival. The transfer time is the easy part; the custody paperwork is what gets challenged.

Why is preparation weighted differently for each route?

Network transfer needs staging and an upload script, which is a fraction of the effort of imaging to shippable media, packaging it, and completing custody documentation — so the model charges the network route a quarter of the preparation time.

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