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Kits and bundles across marketplaces: the stock maths that stops a bundle from overselling
A kit is sold as one thing and ships as several. Its availability is not a number of its own; it is the smallest of its components' available quantities divided by how many of each the kit needs, recomputed on every change to any component, on every channel.
The rule
A kit's available quantity is the minimum, over its components, of each component's available quantity divided by the quantity of that component in the kit, rounded down. A gift set of three mugs and one tray, with 10 mugs and 2 trays available, has 2 available: the tray limits it, and the mugs could make 3.
| Component | Per kit | Available | Kits this component allows |
|---|---|---|---|
| Mug | 3 | 10 | 3 |
| Tray | 1 | 2 | 2 |
| Kit availability | 2 (the minimum) |
Why a kit must never have its own quantity
- If the kit carried a stock figure of its own, selling a mug alone on another channel would not reduce it, and the kit would oversell the moment the mugs ran short.
- The reverse is also true: selling a kit must reserve each component, so the single-mug listing on the other channel sees one fewer mug.
- A component shared by several kits is reserved once per unit, whichever kit or single listing sold it; the kits all recompute from the same component figure.
What the product does
- A kit is defined once, as components and quantities per location. Every number shown for a kit is derived from its components at the selected location; nothing is typed into the kit.
- Selling a kit on any channel reserves its components; the next sweep pushes the recomputed kit availability and the recomputed single-component availability to every channel.
- The Kits screen shows what could ship right now and which component is the one stopping more, so the restock is the right SKU, not the kit.
Several multi-channel tools treat a bundle as a listing with its own quantity, and reviews of them name bundles as the thing that breaks. The maths above is why.