An FNSKU label is the Amazon barcode that tells a fulfilment centre which seller and which listing a unit belongs to. If you send inventory to Amazon.ca through Fulfilment by Amazon (FBA), every sellable unit needs one scannable barcode that Amazon can read and match to your offer, and for many sellers that barcode is the FNSKU. Getting it right is mostly about discipline: the right label, on the right unit, covering the right things, before the carton leaves the warehouse.
In short: print the FNSKU for each listing from Seller Central, apply exactly one scannable barcode to each unit, cover any other barcodes on the product, keep barcodes off the outer carton of case-packed units, and check a sample of every batch before it ships. Most receiving problems come from mixed-up variants, duplicate barcodes and labels that won't scan.
What an FNSKU is (and what it isn't)
FNSKU stands for Fulfillment Network Stock Keeping Unit, Amazon's name for the code. Amazon generates it when you choose Amazon barcodes for an FBA offer, and you can view and print it from your seller account. It identifies your units inside Amazon's fulfilment network so that, when a customer buys from your listing, Amazon picks inventory that belongs to you.
It is easy to confuse three different codes:
- Your SKU is your own internal code. Shopify's help centre describes SKUs as codes you use internally to track inventory and report on sales, and notes that SKUs are different from barcodes and serve different purposes.
- A manufacturer barcode (such as a UPC or EAN printed on the packaging) identifies the product itself, not the seller.
- The FNSKU is Amazon's code for your specific offer in its fulfilment network. It is the barcode Amazon scans when it receives, stores and picks your units.
Keep a simple cross-reference sheet that maps your SKU, the ASIN, the FNSKU and the manufacturer barcode for every variant. Your warehouse, your Shopify catalogue and your Amazon listings then all point to the same product, and nobody has to guess which sticker goes on which colour or size.
Amazon barcode or manufacturer barcode?
In Seller Central you choose how Amazon tracks your FBA inventory: with an Amazon barcode (the FNSKU) or, where the product is eligible, with the manufacturer barcode already on the packaging. Using the manufacturer barcode can save labelling work, because no extra sticker is needed. Using an Amazon barcode keeps your units identified as yours, which many brands prefer for traceability. Amazon's eligibility rules and settings for this choice change over time, so confirm the current options in your account before you plan a shipment.
Whichever option you choose, Amazon's fulfillment guide is clear on the basics: make sure individual units have scannable barcodes, and each unit should only have one scannable barcode. If your product carries a retail barcode and you are applying an FNSKU, the FNSKU label has to cover the original barcode so the scanner can only read one code.
How to print and apply FNSKU labels correctly
1. Print from the right listing
Print labels from Seller Central for the exact listing and condition you are sending. Variants are where most mistakes start: a black and a navy version of the same product look identical on a label sheet, but they have different FNSKUs. Print one variant at a time, and label the sheet or bin with the SKU before anyone starts applying stickers.
2. Use labels that stay scannable
The label needs to scan cleanly at Amazon's receiving dock, not just look right on your desk. Use a printer and label stock that produce sharp, high-contrast barcodes, and avoid labels that smudge, curl or peel. Apply labels to a flat surface where they won't wrap around a corner or sit across a seam. Test-scan the first labels of every print run with a handheld scanner or phone app.
3. Cover every other barcode on the unit
If the product packaging already has a barcode and you are using FNSKUs, place the FNSKU label over it completely. Check all sides of the package: some items carry barcodes on the bottom or the back panel, and inner packaging can carry supplier codes too. One unit, one scannable barcode.
4. Label the unit, not just the bag
Where an item is poly-bagged or bubble-wrapped as part of prep, the barcode must still be scannable through or on the outer layer of that unit's packaging. If you bag after labelling, make sure the bag is clear enough to scan through, or label the bag itself. Loose components that belong to one sellable unit should be bagged or bundled together so they arrive and get scanned as one item.
5. Keep cartons clean
Amazon's guidance for inbound boxes is that shipping boxes should not have any other scannable barcodes except the shipping label, shipping labels should not be placed over box seams, and case-packed units must only have barcodes on the individual units and not on the outer carton. Cover or remove old supplier labels on reused or master cartons before you apply the Amazon shipment ID label.
FNSKU labelling and the rest of FBA prep
Labelling is one step in a sequence. Amazon describes the FBA workflow as setting up FBA, creating listings, preparing products for safe and secure transport according to its packing guidelines and shipping and routing requirements, and then creating a shipping plan, printing shipment ID labels and sending the shipment to Amazon fulfilment centres. Amazon also notes that shipments missing vital prep, labels or packaging can cause problems at receiving.
In practice, the FNSKU work usually happens alongside the rest of prep:
- Inspection on arrival: count and check the units before labelling so damaged or incorrect goods don't get an Amazon label.
- Protective packaging: poly-bagging, bubble wrap or boxing where the product needs it.
- Bundles and kits: a multi-pack or bundle sold as one listing needs its own FNSKU on the outside, and the individual item barcodes inside must not be scannable from the outside.
- Carton build: packing units into cartons that match the shipment plan, then applying the shipment ID labels.
Check Amazon's current packaging and prep requirements in Seller Central for your product type before you start, because prep needs depend on the item. For a product that needs more than a sticker, see our Amazon FBA prep services in Toronto.
Canadian considerations for Amazon.ca sellers
Label at the point of entry, not after a detour
Brands importing from overseas often ship to a prep warehouse first, then on to Amazon. If your goods are coming into Canada, having them received, inspected and labelled at a Canadian facility avoids a second move just to apply stickers. If you are setting up to import as a non-resident business, our CARM registration guide covers the customs side.
An FNSKU is not your product label
The FNSKU only identifies the unit for Amazon. It does not replace the consumer labelling your product needs to be sold in Canada. For example, the Canadian Food Inspection Agency says mandatory information on consumer prepackaged food must be shown in both official languages, French and English. Other product categories have their own federal rules, so confirm your product packaging is compliant before you invest in a large labelled inventory.
Don't cover what must stay visible
When you cover a manufacturer barcode with an FNSKU label, make sure you're not also covering required text, warnings or ingredient information on the package. Placement matters as much as accuracy.
Keep FBM and FBA stock separate
If you also fulfil some Amazon orders yourself through FBM, or sell the same item on Shopify, keep FNSKU-labelled stock separated from unlabelled stock in the warehouse. Our Amazon FBM fulfilment service runs from the same Toronto facility as FBA prep, which makes it simpler to move inventory between channels without relabelling mistakes.
Common FNSKU mistakes and how to avoid them
- Wrong variant label. Print and apply one variant at a time, and scan a sample of finished units against the shipment plan.
- Two scannable barcodes on one unit. Cover the original barcode fully; check every face of the package.
- Labels on the outer carton of case packs. Barcodes belong on the individual units only.
- Low-quality prints. Faded or smudged barcodes can fail to scan; replace worn printer supplies and test-scan.
- Labels across seams or curves. Apply to flat surfaces so the barcode stays readable.
- Relabelling returns blindly. Units coming back from Amazon through removal orders should be inspected before they are relabelled and resent. Our returns and removal orders service handles that inspection and relabelling.
Where Redwolf fits
We run FBA prep from our Toronto facility at 160 Tycos Drive, near Pearson (YYZ). We receive inventory directly from manufacturers and countries of origin, inspect it on arrival, and handle FNSKU labelling and barcoding, poly-bagging and protective packaging, kitting and light assembly before forwarding it to Amazon. Redwolf was founded by an active Amazon seller, you get direct access to the warehouse team rather than a ticket queue, and we can send photos or video of your inventory on request. There are no long-term contracts.
If your products need labelling and prep before they reach Amazon.ca, tell us what you're bringing in and we'll walk through the prep scope with you.
Frequently asked questions
What is an FNSKU label?
An FNSKU label is Amazon's barcode for your specific FBA offer. It tells the fulfilment centre which seller and listing a unit belongs to. You print it from Seller Central and apply it to each sellable unit so Amazon can scan it at receiving and when picking orders.
Is an FNSKU the same as a UPC or SKU?
No. Your SKU is your own internal inventory code, and a UPC or EAN is a manufacturer barcode that identifies the product. The FNSKU is Amazon's code for your offer inside its fulfilment network. Many sellers track all three for each variant.
Do I need FNSKU labels if my product already has a barcode?
It depends on the barcode setting for your FBA offers in Seller Central. Eligible products can be tracked using the manufacturer barcode; otherwise you apply an Amazon barcode. If you apply an FNSKU, it must cover the existing barcode so each unit has only one scannable barcode.
Where should the FNSKU label go?
On a flat surface of each individual unit's outer packaging, covering any other barcode, without wrapping around edges or covering required product information. For case-packed units, barcodes go on the individual units only, not on the outer carton.
Can a 3PL apply FNSKU labels for me in Canada?
Yes. An FBA prep warehouse can receive your inventory, inspect it, apply FNSKU labels, prep and pack it, and send it to Amazon. Redwolf 3PL does this from Toronto for Amazon.ca sellers and brands importing directly from their manufacturers.
Sources
- Amazon.ca — Fulfilment by Amazon (FBA)
- Amazon.ca — Guide to e-commerce fulfillment
- Shopify Help Center — Using SKUs to manage your inventory
- Canadian Food Inspection Agency — Bilingual food labelling