Landed cost calculator: Excel in, quoted costs out

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Pyodide + openpyxl, cached by your browser after the first load.

Row	Item ref	Warehouse	Mode	$ / carton	Storage / mo	Ctns / cont	Pallets / cont	Ctns / pallet	$ with factory	Mode decision reason

Domestic cost per carton is rounded up to the cent and excludes storage; the 1-month storage figure is separate so a quote can extrapolate to any storage duration.

Row	Item ref	Everything wrong with the row, reported at once

Bad rows never calculate silently. Every violation on a row is collected in one pass, so staff fix the row once instead of iterating.

Time	File	Item	Warehouse	Mode	$ / carton	Floor total	Palletized total

Rolling append-only log, one row per calculated quote. Both mode totals are retained even though only one is billed. In the desktop app this lives in audit_log.csv next to the tool.

What this is

A working twin of a Python + Tkinter desktop application (packaged to a standalone Windows .exe with PyInstaller, so staff need no Python install). The calculation engine, the validation layer, and the Excel writer you are exercising here are the same source files the desktop app runs, executed in your browser via Pyodide. 78 unit tests cover every rule: unit conversion, per-carton minimums, container weight vs volume binding, density-tiered pallet caps, the mode decision order, threshold comparisons, cent rounding, validation, and the audit log.

Rate table + packing constants

What this is