A packing quote needs outer dimensions and the applicable service rules, not only the product’s scale weight. Agree the packed box and the provider’s current factor before comparing quote inputs. Do not copy a volumetric factor from one courier into every shipping integration.
Who should use this acceptance brief
Online sellers sending bulky lightweight products. Use this as a scoped website handover task. Where real system evidence is required, teaching examples are not a substitute.
Source-bound platform fact
Australia Post distinguishes eligible size-based flat-rate packaging from other packaging assessed using actual or cubic weight, whichever is greater, under the relevant service conditions. Australia Post: Parcel Post · Checked 16 October 2026.
Filled teaching example
Synthetic example, not a client case. Finite inputs, expected decisions and counterexamples follow; no live integration is claimed.
On narrow screens, scroll to read the complete table.
| Input / case | Check basis | Expected decision |
|---|---|---|
| 40×30×20cm; factor250kg/m³ | hypothetical factor | volume0.024m³; cubic6kg |
| actual2kg, cubic6kg | model max | 6kg model input |
| factor unknown | provider rule missing | unknown |
Run the acceptance exercise
- Measure the closed packed box and record the dimensions’ units.
- Identify the actual service, packaging eligibility and approved factor from current provider terms.
- Compare test quote inputs and displayed charges with the provider’s own authorised calculation.
Interpret the result and retain evidence
The fixture’s250factor is explicitly hypothetical, not a claimed Australia Post tariff. It converts centimetres to cubic metres and chooses a model chargeable mass; it outputs no price. If the package qualifies for another service rule, that max formula may not apply at all. Keep that applicability decision beside the dimensions.
Limits before implementation
No real shipping quote, current price or delivery guarantee. Irregular shapes and provider rounding rules require separate evidence.
Replay the finite example
Save both files in one folder and run with Node22.13 or newer. The example sends no network requests and changes no account or site. Filled inputs and expected outputs · Inspectable functions
node decision-check.mjs parcel-cubic-weight-assumption.json