Amazon FBA Barcodes: UPCs and FNSKUs Explained
QR & Barcode Standards Specialist · Last updated Jul 2, 2026
Fulfillment by Amazon (FBA) is an incredible logistical engine that allows small brands to scale globally by leveraging Amazon's massive warehousing and shipping infrastructure. However, feeding products into that engine requires strict adherence to Amazon's automated receiving protocols.
If you send a box of products to an Amazon fulfillment center and the barcodes are incorrect, unreadable, or missing, the automated conveyor belts will spit your products into a holding area. Your inventory will be stranded, your launch will be delayed, and Amazon will hit you with expensive manual processing fees.
Navigating Amazon's barcode requirements is notoriously confusing for new sellers, specifically the critical distinction between Manufacturer Barcodes and Amazon Barcodes. In this guide, we break down exactly what codes you need, when you need them, and how to format them for flawless FBA intake.
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Create Your Free Code NowThe Manufacturer Barcode (UPC/EAN)
Every product listed on Amazon requires a global product identifier. For most physical goods, this is a standard GS1-issued UPC-A or EAN-13 barcode. This is the Manufacturer Barcode.
When you create your initial product listing in Seller Central, Amazon will demand your UPC. This proves to their database that the product is a legitimate retail item. In some specific scenarios, you can use this exact UPC to track your inventory into the warehouse. This is called 'Commingled Inventory'.
If you choose commingled tracking, Amazon will store your inventory in a giant bin alongside the identical products of every other seller offering that item. When a customer orders from you, Amazon simply grabs a unit from the shared bin. While this saves you from applying special stickers, it exposes you to catastrophic risk if another seller sends counterfeit units into the commingled pool.
The Amazon Barcode (FNSKU)
To protect your brand and ensure you get credit for the exact units you manufactured, you should almost always use the Amazon Barcode system. These specific barcodes are called FNSKUs (Fulfillment Network Stock Keeping Unit).
An FNSKU is a proprietary barcode generated by Amazon that uniquely identifies your specific business as the seller of that specific item. If you send 1,000 units labeled with an FNSKU, those units belong exclusively to you. They are never commingled with other sellers' inventory.
FNSKUs utilize the standard Code 128 barcode symbology. When you finalize your shipping plan in Seller Central, Amazon will generate a PDF of these FNSKU labels. You must print these labels and apply them to your products before shipping them to the fulfillment center.
The Golden Rule: Cover the UPC
This is the most common and costly mistake new FBA sellers make. If you choose to use FNSKU tracking, there can only be ONE scannable barcode visible on the outside of your product packaging.
If your product packaging has a UPC printed on it by the manufacturer, you must physically cover that UPC with the FNSKU sticker. If an Amazon warehouse worker scans the box and the laser catches the UPC instead of the FNSKU, the automated system will reject the unit because the shipping plan expected an FNSKU.
If your packaging has multiple old barcodes, QR codes, or random supplier inventory codes, they must all be covered with blank white stickers or struck through with a thick black marker. Only the FNSKU must survive.
Formatting and Printing FNSKU Labels
Amazon has incredibly strict requirements for how FNSKU labels are printed. You cannot simply shrink them down or print them on colored paper.
The label must contain three specific elements: the scannable Code 128 barcode, the alphanumeric FNSKU text string directly below the barcode, and the text name of the product (to assist human workers).
The labels must be printed with black ink on non-reflective, pure white stock. Amazon strongly recommends printing on standard thermal labels (such as Avery templates) measuring between 1x2 inches and 2x3 inches. Using a high-quality thermal printer (like a Dymo or Zebra) is vastly superior to a standard inkjet printer, as inkjet ink can easily smear during transit, rendering the barcode useless.
Box-Level Barcodes (Carton Labels)
Do not confuse the FNSKU (which goes on the individual, sellable units) with the FBA Box Label.
When you pack 50 of your FNSKU-labeled products into a large master shipping carton, you must apply a completely different set of barcodes to the outside of that master carton. Amazon provides these specialized FBA Box Labels during the final step of the shipping plan.
These box labels tell the inbound receiving dock exactly what is inside the giant brown box and who it belongs to. Never put an FNSKU on the outside of a master carton, and never put a Box Label on an individual, sellable unit.
Tips & Best Practices
- Tip 1: Always use GS1-sourced UPCs when initially creating your Amazon product listing.
- Tip 2: Opt out of 'Commingled Inventory' and always use Amazon FNSKU barcodes to protect your brand.
- Tip 3: Ensure the FNSKU sticker completely covers the original manufacturer's UPC on the packaging.
- Tip 4: Print FNSKU labels using a dedicated thermal printer to prevent ink smudging during transit.
- Tip 5: Ensure there is only ONE scannable barcode visible on the exterior of the final sellable unit.
Frequently Asked Questions
Can I print the FNSKU directly onto my packaging to save money on stickers?
Yes. You can download the FNSKU barcode from Seller Central and incorporate the vector image directly into your packaging design before doing a mass manufacturing run. Just ensure it adheres to sizing and white-space requirements.
What barcode symbology does the FNSKU use?
FNSKUs utilize the standard Code 128 symbology. If you ever need to generate one manually (though downloading the PDF from Amazon is preferred), you can generate a Code 128 barcode matching the alphanumeric string.
Will Amazon label my products for me?
Yes. Amazon offers the FBA Label Service for a per-unit fee. You send them products with a standard UPC, and their warehouse workers will manually apply the FNSKU stickers for you. However, doing it yourself is significantly cheaper.
Can I use a QR code instead of a barcode for FBA?
No. Amazon's automated inbound receiving infrastructure is heavily reliant on fast, linear 1D laser scanners. You must use the linear 1D barcodes they provide.