UPC, FNSKU, and Labeling Rules for FBA Shipments from China

If your products ship from a Chinese factory straight to an Amazon fulfillment center, labeling is one of the most common reasons shipments stall at receiving. Barcodes and carton labels decide whether Amazon can identify your inventory, and since a rule change in March 2026, what used to be optional for many sellers is now mandatory. Get the barcode choice wrong and units are flagged as non-compliant. Get a label placement wrong and the carton is rejected or reworked at your expense.

This guide covers which barcode your business needs, the exact label specifications, and how to brief a Chinese factory or prep partner so everything arrives correct. Getting labeling right at the factory is far cheaper than fixing it after the shipment lands.

UPC vs FNSKU: Which Barcode Does Your Shipment Need?

A UPC is a manufacturer barcode. It identifies the product itself, no matter who sells it. An FNSKU (Fulfillment Network Stock Keeping Unit) is an Amazon-assigned identifier that ties one unit to one seller account and listing. The UPC says "this is this product." The FNSKU says "this is this product, and it belongs to this seller's FBA inventory."

For most sellers sourcing from China, the answer is straightforward: you need an FNSKU label on every unit you send to FBA, unless you are the brand owner enrolled in Amazon Brand Registry with Brand Representative status. That exception is the only remaining path for using manufacturer barcodes without FNSKU stickers. It follows Amazon's March 31, 2026 change that ended stickerless commingled inventory for everyone else, as documented in seller coverage of the 2026 FBA barcode rule change.

Until that change, many sellers used commingled inventory: Amazon pooled identical units from different sellers into shared bins and tracked them by manufacturer barcode. The system saved labeling costs but created accountability problems, since a customer could receive a defective or counterfeit unit that a different seller had sent in. That arrangement is over, and Amazon also discontinued its own paid FNSKU labeling service for sellers, as reported in early 2026. There is no longer a "fix it at the warehouse" fallback, so labeling has to be solved before the goods leave China.

The rule now works differently depending on your seller type:

Seller type · Barcode rule since March 31, 2026

• Brand owner, Brand Registry enrolled with Brand Representative status: May use manufacturer barcode (UPC, EAN, ISBN) without FNSKU stickers
• Private label seller, not yet in Brand Registry: FNSKU on every unit until Brand Representative status is granted
• Reseller of another brand: FNSKU on every unit, even with a valid UPC on the packaging
• Bundles and sets you create: FNSKU for the bundle listing on the outer packaging

One practical consequence: if your Chinese supplier prints a UPC on your packaging and you are a reseller or an unregistered brand, someone has to cover that barcode and apply the FNSKU. Decide which barcode applies before you approve the packaging artwork, because changing it later means reprinting or re-stickering the whole run. Amazon also adjusts these policies periodically, so check your barcode preference settings in Seller Central before every new shipment and treat Seller Central, not third-party guides, as the ground truth.

FNSKU Label Specifications, Written for a Factory Brief

Amazon's receiving scanners need one scannable barcode per unit, and the label has to survive the journey from a factory floor to a fulfillment center. The specifications below translate directly into supplier instructions.

Size. The standard FNSKU label is 1 inch by 2-5/8 inches, printed 40-up on a US Letter sheet (52.5 mm by 29.7 mm, 40-up on A4). A 1 by 2 inch label is also commonly accepted. The barcode must be large enough to scan cleanly, and the human-readable FNSKU number, which starts with "X00", prints beside or below it. If your supplier normally works with tiny stickers, say explicitly that FBA labels need to be at least this size. A label that fits the packaging but is too small to scan is a rejection.

Print quality. Print at 300 DPI or higher on a thermal or laser printer. Inkjet ink smears in humidity and transit, and many suppliers default to inkjet unless told otherwise. Use matte, non-reflective label stock so the barcode reads under warehouse lighting. No smearing, no fading, no wrinkles, no peeling corners.

Placement. One label goes on the exterior of each sellable unit, on a flat surface that is easy to access. It must not run across a seam, an edge, or a curved surface, and it must completely cover any existing manufacturer barcode. Two visible barcodes means the scanner cannot know which to trust, and that is one of the most frequent reasons units are flagged. For polybagged products, the label goes on the outside of the bag.

Verification. Before the full print run, have five units labeled and scanned, or ask for clear photos of the labels. Confirm the barcode reads as the correct FNSKU and the human-readable number matches your listing.

Carton and Pallet Labels: The Shipment-Level Barcodes

Unit labels identify products. Carton labels identify the shipment, and Amazon cannot route your boxes without them. Every shipping carton needs its own unique FBA box ID label, generated from the Shipping Queue in Seller Central when you create the shipment, linking that specific carton to the SKU list, quantities, weights, and dimensions you declared.

Place the box label on a flat surface of the carton where it stays scannable, never on the bottom and never folded over an edge or corner. Do not cover the label with tape, and do not slip it into a plastic pouch. Both are common habits from general freight shipping, and both make the barcode unreadable at intake. If you reuse cartons, remove or completely cover every old shipping label and barcode mark. Leftover marks from an old shipment are a classic source of receiving delays.

If anything changes after printing, reprint the whole set. Amazon's guidance is explicit: change the number of boxes or their declared contents and you reprint the entire label set, because each box ID is tied to a specific declared content list. A mismatch between the label and the actual contents causes delays at best and a rejected shipment at worst.

Each pallet needs four FBA pallet ID labels, one centered on each side, and every box stacked on the pallet still needs its own box label. Neither replaces the other. Every carton is also subject to weight and dimension limits: no more than 50 pounds and no more than 25 inches on any side. If one sellable unit is genuinely heavier than 50 pounds, label the carton "Team Lift" on the top and sides. Master cartons leaving China should carry the country of origin marking, typically "Made in China," alongside the shipment ID and unit count.

Five Labeling Mistakes That Get Shipments Rejected

Most rejections trace back to a small set of mistakes, and nearly all are easier to prevent in China than to fix after import.

First, the double barcode. A unit arrives with both the manufacturer UPC and the FNSKU visible, so the scanner cannot know which to trust, and the batch gets flagged. The FNSKU label must fully cover the UPC, not sit beside it.

Second, labels on seams, curves, or edges. A label wrapped around a box corner wrinkles; one on a curved bottle lifts at the edges. Tell your supplier exactly where the label goes and reject batches where labels were applied wherever was convenient.

Third, tape over the barcode. Shippers often run packing tape across labels to "protect" them. Amazon requires the label to remain uncovered and scannable, and a barcode under glossy tape reflects scanner light and fails to read.

Fourth, the wrong label file. A supplier prints FNSKU labels from an old shipment's PDF, or mixes up two SKUs' labels in one run. This happens most often when the supplier labels from files saved on their own computer instead of the fresh file you sent. Send the label PDF named by shipment ID and have the supplier confirm the X00 code matches before printing.

Fifth, missing warnings and set labels. A polybag with an opening of five inches or more must carry a suffocation warning, and items sold as a set must be marked so they are not separated. These are packaging labels rather than barcodes, but receiving staff enforce them just as seriously, and they are the most commonly forgotten items on a first shipment.

Where to Get the Labeling Done: Factory, Prep Center, or Home Country

For a China-origin FBA shipment there are three realistic options, and the right one depends on your order size, how much you trust the supplier, and your timeline.

Option · How it works · When it wins

• Label at the factory: Supplier prints and applies FNSKU labels, polybags, and set labels during or right after production · Cheapest per unit; works when the supplier is trusted, labeling is simple, and QC verifies the work
• Label at a China prep center: Finished goods ship to a prep warehouse (often in Shenzhen, Yiwu, or Ningbo) that applies Amazon-spec labels, repacks, and consolidates before international freight · Complex labeling, multi-supplier consolidation, or a supplier you have not tested yet
• Label in the destination country: Goods ship to you or a domestic prep center first, adding a domestic shipping leg · Neither upstream option can be verified, or the product needs work only you can do

As a cost benchmark, published FBA prep guides commonly quote FNSKU labeling around five to fifteen cents per unit in China versus twenty to forty cents in the US. Those are planning benchmarks, not quotes; actual pricing varies by product and region. What does not vary is the direction. Labeling done in China is materially cheaper than labeling done after import, and catching a labeling error during a pre-shipment inspection in China is dramatically cheaper than catching it at an Amazon dock.

Many growing sellers settle into a hybrid: the factory applies the simple FNSKU stickers while a prep center handles the fiddly parts, polybagging with suffocation warnings, sets, carton labels, and the final check. That split keeps unit costs low while putting the most error-prone steps in specialist hands.

How to Brief a Chinese Supplier on Labeling

A supplier that has never done Amazon labeling will get it wrong by default. A written brief, attached to the purchase order, closes that gap.

Send the exact label files first. Generate the FNSKU PDFs in Seller Central for the specific shipment and send them with the shipment ID in the file name. State explicitly that these files replace any labels saved from previous orders, and ask the supplier to confirm the human-readable FNSKU code before printing. Files get mixed up on factory computers more often than anyone admits.

Specify the physical requirements in plain terms: label size, 300 DPI thermal or laser printing, matte labels, one label per unit on a flat exterior surface, existing barcodes fully covered, no tape over the barcode. For polybagged products, add the suffocation warning requirement for bags with a five-inch or larger opening. For sets, specify the "sold as set, do not separate" label on the outer packaging.

Require proof before the bulk run. Ask for photos of at least five labeled units showing placement and the covered manufacturer barcode, plus confirmation that the barcode scans to the correct FNSKU. Fold label verification into your normal quality control checklist so the inspector checks placement, readability, and warning labels as a line item. Handle carton labels separately from unit labels: they are generated later in the shipment flow and change if box counts change, so the supplier or forwarder should apply them only after you send the final set. Reusing cartons across orders is common in China, so require all old labels to be removed or fully covered first.

Polybags, Sets, and Bundles: The Extra Labels People Forget

Polybags with an opening of five inches or more must display a suffocation warning on the prominent face of the bag, either printed on the bag or applied as a separate label, with the font sized appropriately for the bag. Many Chinese packaging suppliers stock standard warning-printed polybags. Verify the warning is present on the sample bags before approving the run.

Sets and bundles sold as one listing must be packaged together and labeled so they are not separated at the fulfillment center. The standard marking is a "Sold as Set" or "Do Not Separate" label on the outer packaging, with the bundle listing's FNSKU on that same outer packaging. If inner units each carry their own barcodes, cover them or arrange things so the bundle's FNSKU is the only scannable code on the outside.

A bundle is your own listing with its own FNSKU, which means it was never eligible for stickerless tracking in the first place. Label it as a labeled unit from day one and you sidestep the entire rule-change discussion for that SKU. For more on structuring bundles for FBA, see our guide to product bundling with goods sourced from China.

Frequently Asked Questions

Can my Chinese supplier apply FNSKU labels for me?

Yes, and it is usually the cheapest option. Generate the FNSKU label files in Seller Central, send the supplier the PDFs for the specific shipment, and specify label size, print method, and placement in your purchase order. Require photos or a scan test of labeled sample units before the bulk run.

Do I still need FNSKU labels if my product already has a UPC?

It depends on your seller type. Brand owners with Brand Representative status in Amazon Brand Registry can use the manufacturer barcode without FNSKU stickers. Everyone else, including resellers and brands not yet enrolled, must apply FNSKU labels to every unit even when a valid UPC is printed on the packaging. The existing UPC must be fully covered by the FNSKU label.

What size should FNSKU labels be?

The standard is 1 inch by 2-5/8 inches, printed 40-up on US Letter sheets (52.5 by 29.7 millimeters, 40-up on A4). A 1 by 2 inch label is also widely used. Print at 300 DPI or higher on a thermal or laser printer with matte, non-reflective stock, and confirm the barcode and the human-readable X00 number match your Seller Central listing before the full batch.

Can Amazon still label my products for me?

Amazon discontinued its paid FNSKU labeling service for sellers, as reported in early 2026, so you can no longer pay Amazon to apply labels at the fulfillment center. All labeling has to happen before the inventory arrives, which makes the factory, a China prep center, or a domestic prep step your only options.

Do I need new carton labels if Amazon splits my shipment?

Yes. Each fulfillment-center destination is a separate shipment with its own shipment ID and box ID labels. Generate the carton labels for each destination separately and make sure each physical carton carries the label matching its actual destination and contents. If box counts or contents change after printing, reprint the full set rather than patching individual cartons.

The Decision Rule: Where Your Labels Get Applied

By the time a container leaves China, every label decision is already locked in, and the only remaining question is how much the fix costs.

The decision rule most experienced FBA sellers land on is simple. If the labeling is one FNSKU sticker per unit and you trust the supplier, have the factory do it and verify the work during QC. If the labeling involves polybags, sets, multiple SKUs, or a supplier you have not tested, route the goods through a China prep step where labeling is the core competence. What you should not do is ship unlabeled inventory and hope Amazon sorts it out, because since the service changes of 2026, that option no longer exists.

If labeling, prep, and China-side quality checks are the parts of your FBA workflow you would rather not manage by email and hope, CN Ally's Amazon FBA prep support handles labeling verification, polybagging, carton compliance, and consolidation in China before your shipments leave. For the full surrounding requirements, our guide to FBA prep requirements for shipments from China covers packaging, inspection, and freight handoff in one place. If you want a second pair of eyes on your next shipment's label files before they go to the factory, write to hi@cnally.com.