Sending Products to Amazon FBA: What Actually Happens Between Your Warehouse and Theirs

It's a workflow, not a shipment

"Sending to FBA" sounds like one action. It's actually six decisions stacked on top of each other, and each one changes your cost or your risk of a hold. You decide which SKUs go into the shipment and whether it's one box or several going to different fulfillment centers. You decide who preps each unit — Amazon or you — and whether it needs poly bagging, bundling, or a suffocation warning label. You decide how it ships: Amazon's partnered carrier, your own LTL account, or a freight forwarder. Then you print labels, book the dock appointment, and — the step almost every guide skips — check that the units Amazon says it received match the units that actually left your warehouse.

Get any one of those wrong and the shipment doesn't just cost more. It gets held at receiving, split across more centers than you planned, or shows up short with no clean paper trail to prove otherwise.

The six stages, in order

Amazon's own Send to Amazon workflow walks you through creating the shipping plan, choosing prep, labeling, packing, and picking a carrier. What it doesn't walk you through as clearly is the last stage — reconciling what you shipped against what got receipted — which is where most of the money actually leaks. The table below is the same six stages, with the failure mode attached to each one.

A worked example: why box count changes the bill

Say you're shipping 1,000 units of a mid-size item. Send it as one shipment and Amazon may route it all to a single fulfillment center, or split it for you — either way, you pay whatever inbound placement fee applies to that routing. Split it yourself into smaller lots aimed at specific centers to dodge that fee, and you're now paying your own freight to move boxes further, on your own dime, to hit "minimal splits." There's no universal right answer here — it depends on your item's weight, dimensions, and where your demand actually sits — but it's a real trade-off you're making every time you create a shipping plan, not a default setting to leave alone.

The same logic applies to dimensional weight. A light item in an oversized box gets billed on its dimensional weight, not its actual weight, because Amazon bills whichever is higher. A 2-lb item that boxes up to 6 lbs of dimensional weight gets charged like a 6-lb item, shipment after shipment, until someone catches it. That's a fee-structure fact, not a one-time glitch — it repeats on every unit of that SKU until the packaging or the listing gets fixed.

The mistake we see most, including our own

The most common error isn't the shipment itself — it's the prep category chosen when the listing was created, weeks before anyone thought about shipping. Pick "individual" prep for something that actually needs poly bagging under Amazon's suffocation policy, and the box doesn't get rejected outright — it gets flagged, sits in receiving limbo, and quietly delays your in-stock date while you're mid-launch or mid-campaign. We've had this happen on our own book: a shipment held for days over a prep mismatch that a five-minute listing check would have caught before the boxes ever left the dock.

The second most common mistake is treating the shipping plan as a one-time setup instead of a per-shipment decision. Split ratios, carrier choice, and prep requirements can all be right for one SKU and wrong for the next one in the same box.

When the receipt doesn't match the shipment

This is the part the ranking pages skip. You ship 1,000 units. Amazon's dashboard shows 970 received. That 30-unit gap is either a counting error, damage in transit, or a real loss — and Amazon gives you a limited window to file a discrepancy claim with your bill of lading and carrier receipt attached. Miss that window and the units are gone, full stop, no reimbursement. At even a modest average sale price, 30 units missing on one shipment adds up fast once you're running dozens of shipments a year across a full catalog — and across the brands we manage inventory for, discrepancy and reimbursement recovery is consistently one of the larger recoverable amounts, not a rounding error. Full Circle has managed more than $500M in revenue across 100+ brands, and the same pattern shows up at almost every scale: the freight bill gets scrutinized, the receiving discrepancy does not.

If the number looks wrong, don't wait for the next shipment to "average it out." Pull the carrier's proof of delivery, check the unit count against your own outbound records, and file inside the window. If the fix doesn't stick — units still short, reimbursement denied without explanation — escalate with the paperwork attached rather than resubmitting the same claim.

What this doesn't cover

Sending to FBA is about getting inventory into Amazon's network. It says nothing about why a SKU needed reordering in the first place, whether it's about to hit aged-inventory surcharges, or whether the fee charged on last month's shipment was even calculated correctly. If your stockouts trace back to a slow ad account rather than a slow reorder — spend pulled forward, budgets capped too early, a campaign that outran the inventory behind it — that's a Dr. PPC problem, not a shipping one.