The Supplier Routing Guide for Amazon-Bound Freight: What to Send the Factory Before the PO Ships

By Bernardo Campelo, Forbes Business Council E-Commerce Leader, Amazon SPN Certified provider, Amazon SP-API authorized partner, and Founder of PrepVia.

As of October 29, 2026, Amazon's own page on seller requirements for LTL, FTL and FCL deliveries tells sellers to download its ocean container preparation guidelines, in English and in Chinese, "to print out and share with your supplier or factory." The same page says that following its requirements, and "making sure that your carriers and suppliers follow them," makes it easier to get shipments accepted.

That written set of rules is a supplier routing guide. Large retailers publish routing guides for their vendors, often next to an EDI connection. A factory with no EDI connection still has a carton spec, a pallet spec and a packing list, and those three documents decide how the freight gets received.

One thing up front, because the search that brings people here is "3PL without EDI": PrepVia does not offer EDI or ASN transactions; both are on its "Not offered" list. This guide covers what a brand can send a factory so that EDI is never needed in the first place: the carton, the pallet, the container and the packing list, each tied to Amazon's published rule.

Every date and name below was checked on October 29, 2026 against Amazon Seller Central Help, Amazon's ocean container guidelines, X12 and the Hong Kong government's holiday list, linked where they first appear. Amazon edits these help pages without notice, so recheck a number before copying it.

Why the Factory Needs a Written Guide, Not an EDI Feed

In the X12 standard, the document that describes a shipment before it arrives is the 856 Ship Notice/Manifest. X12 says it "can be used to list the contents of a shipment of goods as well as additional information relating to the shipment, such as order information, product description, physical characteristics, type of packaging, marking, carrier information, and configuration of goods within the transportation equipment." In retail, that file is usually called an ASN, an advance ship notice.

Every item on that list also appears on a good packing list: what is in each carton, how it is packed, how it is marked, how it is loaded. The 856 is a format for sending that information between two systems. A factory without EDI puts the same information on paper, a spreadsheet or a PDF.

So the real problem is not the missing file. A factory that has never been told what Amazon requires packs to its own habits: its usual carton size, its usual shipping marks, its usual pallet, and a packing list in its own layout. A routing guide replaces those habits with your spec. If you work with a retailer that does run on EDI, the posts on case packs, pallets, LTL and EDI and on Vendor Central vs Seller Central cover where those documents actually begin.

It matters more in 2026. According to Amazon's FBA Prep Service page, "Starting January 1, 2026, we'll no longer offer prep and item labeling services for Fulfillment by Amazon (FBA) shipments in the US store." Whatever the factory leaves undone has to be finished before the units reach Amazon.

Two Routes, Two Guides: Direct to Amazon or Through a Prep Center

Before writing a carton rule, decide where the freight goes when it lands, because the guide changes with the destination.

Direct to an Amazon fulfillment center. Amazon's shipping and routing requirements cover this case directly: "Make sure your distributor has the correct Amazon FBA Box ID labels for your shipment. You can grant limited access to your seller account to access labels." The page adds that "your distributor must adhere to all Amazon shipment requirements." Amazon's ocean container guidelines are built for this route too: "Create shipment plans in Seller Central and print FBA shipment labels before booking the shipment with the carrier." On this route, the factory is applying Amazon box labels, so the Amazon shipment has to exist before the freight leaves.

Through a prep center first. Here the factory is shipping to a warehouse, not to Amazon. The Amazon box ID label is tied to a shipment ID that usually does not exist yet when the container is loaded, which is why the factory should go no further than unit-level FNSKU labels and its own carton marks. The post on FCL box labels, loose vs palletized explains in detail why a factory-printed Amazon box label goes wrong on this route. The carton and pallet sections below apply either way; what changes is who applies the Amazon labels, and when.

Whichever route you pick, put it on the first page of the guide in one sentence, with the ship-to address.

The Carton Section: Amazon's Box Rules, Copied Into Your Spec

A carton that breaks Amazon's limits has to be repacked before it can go to a fulfillment center. Amazon's shipping and routing page sets the standard limits: "Dimensions: 36.00"(L) x 25.00"(W) x 25.00"(H), and weight: No more than 50.00 lb total. These limits apply unless the box contains an individual oversize item that exceeds these dimensions or weight." It also says "Boxes containing jewelry or watches must not exceed 40.00 lb."

The same page contains a second, conflicting sentence that allows up to 65 lb. Use 50 lb in your guide. It is the limit the same page states twice and the one Amazon's container guidelines use, and a factory will read a carton spec with exceptions as permission to pack heavier.

Amazon does not supply the Team Lift or Mechanical Lift labels. Its page says sellers "may generate it by yourself" in the local language of the destination country, so the guide should tell the factory to print them in English for US freight.

From the same page: "Do not use pallet-sized boxes (also known as "gaylords")." "Don't use string, straps, or over-wrap (plastic or paper)." And "Do not bundle multiple boxes together."

The case pack rules on Amazon's product packaging requirements page are easy to break without knowing it. Amazon's example: "a case pack of 24 units must always contain 24 units." A master carton holding several inner case packs does not count as a case pack and "must be separated at the appropriate case-pack level," so the guide has to say whether the master or the inner is the shipping unit.

At the unit level, "Any FNSKU you use on a unit must be unique and must correspond to one unique product," so each size or color gets its own. For expiration-dated products, "Lot numbers alone are insufficient." The ocean container PDF prints a different date format and a 90-day rule. Use the help page's date format, and take shelf life from Amazon's expiration dates page: at check-in, a product needs enough shelf life left to be "consumed in full, plus an additional 90 days," and the page lists a minimum by category.

The Pallet and Container Section

Amazon's LTL, FTL and FCL page says: "Use 40 x 48 inches, 4-way access wooden pallets," on "GMA Standard B Grade or higher pallets," and "Ship grocery products on GMA 1A Grade pallets only." Amazon also says "Only GMA 1A and 1B Grade pallets are acceptable for health & personal care and beauty products."

• Weight and height. "Total weight of the pallet must not exceed 1,500 lb. Single pallets must not be higher than 72 inches, including the height of the pallet, unless a single unit is taller than 72 inches."
• Wrap. "All pallets must be wrapped in clear plastic stretch wrap," with a "Do not break stretch wrap" or "Do not break down" note to the carrier. The container PDF adds: "Do not use black or opaque stretch-wrap."
• Separation. "When shipping multiple ASINs on a pallet, physically separate the ASINs so that they are easy to differentiate upon receipt." A pallet holding one ASIN gets labeled "Single ASIN pallet."

For the container itself, the same page asks for 6 inches of clearance "from the top of the stack to the roof of the container," at least 3 inches "between pallets and walls," and at least 8 inches "from the last row of pallets to container doors to engage a dock leveler." For a factory in China, attach the Chinese edition of the container guidelines instead of translating Amazon's rules yourself.

Fluid floor-loaded containers have their own rules in the PDF. Only standard-size (sortable) ASINs go fluid floor-loaded, cartons bound for a sortable fulfillment center measure less than 25 inches on each side and stay at or under 50 lbs, and Amazon recommends "no more than 5 different ASINs in the box" when a single ASIN per carton is not possible. Oversize units go on pallets or in a clamp truck load. The post on floor-loaded FCL through a prep center covers how each load type changes the unload; the guide only has to say which one you chose.

The Packing List Section: The Document That Replaces the 856

If the factory will never send an 856, the packing list has to carry what the 856 would have carried. Amazon's own pack list template is a good minimum. On its box content information page, the instruction is: "For each box, enter the number of units per product, expiration dates (if applicable), and the box weight and dimensions." A factory packing list that gives you those four things per carton gives you what Amazon will ask for.

Ask for weights and dimensions on either route. Amazon's shipping and routing page says "Accurate box weight and dimensions are required for all shipments," even without box content information or a partnered carrier, and a factory carton that goes on to Amazon unopened carries the factory's numbers.

Here is what the packing list section of a routing guide can ask for, line by line:

• Header. Your PO number, the supplier name, the ship date, the container or trailer number and the route (direct to Amazon or through a prep center).
• One row per carton, or per run of identical cartons. Carton number range, your SKU, the unit barcode on the product, units per carton and the number of cartons.
• Carton physicals. Gross weight and outside dimensions of each carton, in pounds and inches, measured after packing.
• Dates. Expiration date per SKU per carton where it applies. Amazon's page says "An SKU can have only one expiration date per box," so a SKU with two dates has to be packed in separate cartons.
• Totals. Units per SKU, total cartons and total pallets for the load. Amazon's bill of lading rules ask for "Correct pallet and box count quantities," so the totals on the packing list should match the BOL.
• Marks. The shipping mark printed on each carton, so a carton on the dock can be matched to its row.

If several suppliers share one container, add the supplier code and PO number to the carton marks and a subtotal per supplier on the master packing list. The post on consolidating suppliers into one container gives the exact purchase order wording for that.

There is a fee reason to get box contents right, and in November it doubles. Amazon's FBA manual processing fee applies when box content information is not provided: "$0.15 per unit" from January to October and "$0.30 per unit" from November to December. The rate follows the month the first unit is received, not the month the shipment was created. For the mechanics in Seller Central, see how to add box content to an FBA shipment.

Turning a factory's packing list into an expected count is plumbing nobody notices until a count comes up short. The guide is what makes the document readable: same columns, same units, one row per carton run.

"AI becomes the invisible infrastructure behind your success."

Bernardo Campelo, in a Forbes Business Council article, January 7, 2026

When the PO Says 50 and the Supplier Confirms 30

A costly mistake in this process is building the Amazon shipment from the purchase order instead of from what the factory confirms it packed. Say a brand orders 50 units of a SKU and the factory's packing list shows 30. If the FBA shipping plan was built at 50, the shipment will arrive 40% short of its plan.

Amazon's page on deleted, misrouted and incomplete shipments sets the tolerance: "You can adjust unit quantities by 5% above or below the original amount or up to six units per SKU, whichever is greater. You can't remove units from your plan once you've approved it." On 50 units, 5% is 2.5 units, so the six-unit allowance is the bigger one. That lets the plan go no lower than 44, still 14 units above what the factory packed. The page offers one other way out: delete every shipment in the approved plan before any of it ships, and Amazon lists deleted shipments among the problems that can bring an inbound defect fee too.

The same page says "Shipments that deviate from an approved shipping plan, like sending to the wrong facility or sending significantly different item quantities or ASINs, are non-compliant." Amazon's inbound defect fees page lists "sending incomplete shipments where item quantities differ significantly from your shipping plan" among the problems that can bring a per-unit fee. For shipments created on or after January 15, 2026, those fees run from $0.32 for a small standard unit of 16 oz or less up to $5.72 for the heaviest large bulky tier. Amazon does not define "significantly" on either page.

A short carton is a different problem from a short shipment, and Amazon treats it differently. The box content information page carries a note: quantity discrepancy defects "are no longer eligible for dispute," and the list includes "Inaccurate ASIN Quantity in Carton, Item not on PO, Item Overage, and Unexpected ASIN in Carton." Right below it: "There are no financial consequences or penalties associated with this defect." You cannot argue a wrong carton count, but on that page it does not carry a fee either.

Timing adds a third constraint. Amazon says "Domestic shipments must arrive within 45 days of shipment creation. International shipments must arrive within 75 days of shipment creation. Late shipments will result in notification of non-compliance and will close automatically." A shipment created with the PO starts that clock while the goods are still being made.

Put together, these rules point one way: the factory's confirmed quantity, carton by carton, is the number the Amazon shipment should be built from. The routing guide makes that possible by asking the factory to send the packing list when it packs, before the freight is booked, so a 50-against-30 gap shows up on a document and not on a dock. Comparing the packing list to the PO is the brand's job, and the guide gives it something to compare.

When the freight goes through a prep center, the count happens again at receiving. The post on the wholesale receiving workflow covers reconciliation against the purchase order, and real counts vs said-to-contain covers what a carton count does and does not prove.

Sending the Guide Before Chinese New Year

According to the Hong Kong government's list of 2027 general holidays, Lunar New Year's Day falls on Saturday, February 6, 2027. November and December orders are the ones to send the guide with. A factory in the middle of a pre-holiday run is unlikely to change its carton spec partway through.

The planning calendar for the holiday is in Chinese New Year 2027: your FBA inventory plan. For the guide, attach it to the PO, ask the factory to confirm it in writing before production, and ask for the packing list in your format as soon as cartons are sealed.

A routing guide is a logistics document: customs entry, importer-of-record duties and country of origin belong with your customs broker.

Where a Prep Center Fits

A prep center on the receiving end of factory freight does physical work: it receives the cartons, counts and inspects them, labels and preps the units, packs boxes, builds pallets and creates the inbound shipment to Amazon. It cannot make a packing list accurate after the fact. What it can do is work from that packing list as the expected count and report where the freight differs.

PrepVia, at 8507 NW 72nd St, Miami, FL 33166, receives imported freight, floor-loaded or palletized, and routes it into Amazon FBA. FBA prep covers receiving, inspection, counting, labeling, bagging, box packing, pallet building and inbound shipment creation, and receiving and inspection are included. Discrepancies are reported within 24 hours of arrival, with photos. Outbound freight to Amazon can move by Amazon partnered LTL and FTL, or by small parcel. The prep window is 24-36 hours. Container unloading is quoted per account; floor-loaded containers by carton count.

What PrepVia does not do: EDI and ASN transactions are not offered. A brand that exchanges EDI with a retailer keeps that connection with its own EDI provider. What a factory without EDI can send is what this guide asks for: the packing list, the carton marks and the ship-to.

"A factory that has never sent an EDI file still sends a packing list. We would rather work from the document the factory already has than ask for a format it doesn't."

Bernardo Campelo, Founder of PrepVia

Frequently Asked Questions

Do I need EDI to work with a 3PL or prep center for Amazon freight?

No. For Amazon FBA, what the receiving side needs is a carton spec that meets Amazon's rules and a packing list with units per SKU per carton, weights and dimensions. PrepVia does not offer EDI or ASN transactions.

What should a supplier routing guide for Amazon-bound freight include?

The route and ship-to address, a carton section, a pallet and container section, unit barcode instructions and a packing list format with one row per carton run, each tied to Amazon's published rule.

Should my factory print Amazon FBA box labels?

Only if the freight goes straight to an Amazon fulfillment center. Amazon says your distributor must have the correct FBA Box ID labels, and you can give it limited access to your account to print them. If the freight goes through a prep center first, the Amazon shipment usually does not exist yet when the container is loaded, so the factory should stop at unit labels and carton marks.

What happens if my supplier ships fewer units than my PO?

If the FBA plan was built from the PO, it may be more than Amazon's tolerance can absorb: once a plan is approved, quantities move only 5% or six units per SKU, whichever is greater, and units cannot be removed. Amazon treats shipments with significantly different quantities as non-compliant, which can bring inbound defect fees. Build the plan from the quantities on the factory's packing list.

Can I dispute a carton quantity discrepancy with Amazon?

Not anymore. Amazon's box content page says quantity discrepancy defects, including Inaccurate ASIN Quantity in Carton, Item not on PO, Item Overage and Unexpected ASIN in Carton, are no longer eligible for dispute. The same page says there are no financial consequences or penalties associated with that defect.

Why does box content matter more in November and December?

Amazon's manual processing fee for shipments without box content information doubles, from $0.15 to $0.30 per unit, when the first unit is received in November or December. A packing list with units per SKU per carton lets you fill in box contents and avoid it.

Final Take

Amazon has already written most of the routing guide, and it says to share it with the factory. What the brand adds is the route, the packing list format and the rule that the Amazon shipment is built from the factory's confirmed count, not from the PO.

None of it needs EDI: one document sent with every PO, confirmed before production, and a packing list that comes back in the same format every time.