Tuesday afternoon, and the shipment still is not built
You know the routine. Someone downloads the Restock Inventory report, opens last week's shipment spreadsheet, checks what is sitting at the prep centre, digs out the supplier's packing list to find units per carton and carton weights, and then starts the Send to Amazon workflow in Seller Central. Halfway through, Amazon offers a placement option that splits the shipment across several fulfilment centres, and the plan you had in your head no longer fits the cartons you have.
By the time the labels are printed, the numbers have been typed three times: once into the sheet, once into Seller Central, once into the message to the prep centre. If any of them is wrong, you find out when the shipment is received short or a carton gets flagged for a box content problem.
For a seller with a handful of ASINs this is an annoyance. With a few hundred SKUs, several suppliers and more than one marketplace, it becomes one person's whole week.
The planning is hard because the data is scattered
Amazon gives you most of what you need, but in separate places and in slightly different shapes. The restock suggestions do not know that a container is arriving at your warehouse on Friday. Your stock sheet does not know your current FBA capacity limit for standard-size items. The supplier's carton data sits in a PDF or an email thread, and your prep centre has its own portal with its own counts.
- Sales velocity and days of cover come from Seller Central reports, downloaded by hand.
- Units on hand, in transit and reserved sit in the FBA inventory page, which changes daily.
- Units per carton, carton dimensions and weights are in supplier documents.
- Stock at the prep centre or your own warehouse lives in their system or a separate sheet.
- Capacity limits and placement options only appear once you start a shipment.
So the person building the shipment is really doing data joining in their head, and that is where the mistakes and the lost afternoons come from.
What a messy inbound process costs
The direct cost is time, and it is usually senior time, because the person who knows which SKUs matter is the one who builds the shipment. The indirect costs are harder to see. Stock-outs on a fast seller because the shipment went a week late. Overstock on a slow one because last month's quantities were copied forward. Placement fees you could have reduced if you had known the carton split earlier. Box content errors that lead to manual processing and delays at the fulfilment centre.
There is also the risk of one person being the only one who understands the spreadsheet. When they are on holiday, shipments stop.
The shipment planner we build
- A nightly pull from the Selling Partner API of FBA inventory, inbound quantities, recent sales and your restock data for each marketplace you sell on.
- A product record for each SKU holding units per carton, carton dimensions and weight, prep requirements and labelling, entered once and kept up to date.
- A feed of stock available to send, read from your warehouse system, your prep centre's export or a shared sheet, whichever you already use.
- A suggested shipment for each SKU, based on the days of cover you set, current inbound units, supplier lead time and your capacity limits, rounded to full cartons.
- A review screen where you change quantities, drop SKUs and approve. Nothing is created in Seller Central until you approve.
- On approval, the inbound plan is created through the API with box contents, and a pick list goes to the prep centre or warehouse in the format they already accept.
| Input | Where it usually lives | Where it lives after |
|---|---|---|
| Sales and days of cover | Report downloaded weekly | Pulled nightly per SKU |
| Carton data | Supplier PDFs and emails | Product record, entered once |
| Stock available to send | Prep centre portal or sheet | Read automatically each day |
| Capacity limits | Seen mid-shipment | Shown before you plan |
| Box contents | Typed into Seller Central | Sent with the inbound plan |
The rules for days of cover, safety stock and which SKUs to prioritise are yours, and they can differ by product line or season.
A normal planning day afterwards
On shipment day you open the planner, see a draft with quantities already rounded to cartons and flags for anything unusual: a SKU with no carton data, a product close to its capacity limit, a supplier container not yet received. You adjust a few lines, approve, and the plan is in Seller Central with box contents attached.
The prep centre receives the same numbers you approved, so there is no retyping. When a shipment is received short later, you can compare against exactly what was planned and packed, which makes any follow-up with Amazon simpler.
The spreadsheet does not disappear overnight. Many sellers keep it for a while as a check, and that is sensible.
Signs your inbound planning needs this
- One person builds every FBA shipment and nobody else can.
- You copy last month's quantities forward because recalculating takes too long.
- Carton counts are typed into Seller Central from a supplier PDF.
- You find out about capacity limits halfway through a shipment.
- Your prep centre regularly asks which version of the list is the right one.