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Barcodes for Amazon FBA: FNSKU vs GTIN

New FBA sellers hit the same wall: is the barcode a UPC, or that "FNSKU" thing Amazon mentions? They are two different numbers with two different sources. Here is how they fit together.

EAN Studio · Updated July 2026

Selling with Fulfilment by Amazon involves two kinds of barcode, and confusing them is the most common early mistake. One identifies your product to the world (the GTIN, shown as a UPC or EAN). The other identifies your unit inside Amazon's warehouses (the FNSKU). You generally need both, at different steps.

The two numbers

 GTIN (UPC / EAN)FNSKU
What it isGlobal product identifierAmazon's per-seller unit identifier
Issued byGS1 (when you register)Amazon (Seller Central)
Used forCreating the listing / catalogLabelling units sent to FBA
Barcode typeUPC-A or EAN-13Code 128
Looks like012345678905X00ABC1234

How the flow works

  1. Get a GTIN. Buy a UPC/EAN (a GTIN) from GS1, or use an existing manufacturer GTIN. Amazon generally requires a valid GTIN to create a listing, unless your product qualifies for a GTIN exemption.
  2. Create the listing. Enter the GTIN in Seller Central; Amazon matches or creates the catalog entry.
  3. Amazon issues the FNSKU. When you set the item to "FBA / Amazon barcode", Seller Central generates an FNSKU and a printable label for it.
  4. Label the units. Each physical unit going to FBA carries the FNSKU label (unless it is stickerless / commingled), so Amazon can track your specific inventory.
Where EAN Studio fits — and where it doesn't. EAN Studio does not sell you a GTIN and does not generate FNSKUs — those come from GS1 and Amazon respectively. What EAN Studio does is turn a number you already have into a clean, print-ready barcode image, and help you lay it out on a label. Bring the number; we handle the artwork.

Which barcode do I actually print?

For FBA, the label on each unit is the FNSKU (a Code 128 barcode) that Amazon provides — print that one from Seller Central. The GTIN barcode (UPC/EAN) belongs on the product's retail packaging if you also sell it elsewhere. If you need to reproduce a UPC or EAN image for your own packaging, the UPC-A generator and EAN-13 generator do that; the Code 128 generator handles internal SKU codes.

Rules change — check Amazon's current help pages. GTIN-exemption eligibility, stickerless/commingled options and labelling requirements are set by Amazon and updated over time. Confirm the specifics for your category in Seller Central before a big shipment.

Make the barcode image

Free, in your browser, from a number you already have.

UPC-A generator EAN-13 generator

Related guides

EAN vs UPC How the check digit works PNG vs SVG for printing Code 128 generator

Frequently asked questions

What is the difference between an FNSKU and a GTIN?

A GTIN (the number behind a UPC or EAN) is a global product identifier issued by GS1. An FNSKU is Amazon's own per-seller identifier, generated inside Seller Central, used to tie a physical unit to your specific listing in Amazon's fulfilment network.

Do I need a UPC to sell on Amazon FBA?

Usually yes — Amazon generally requires a valid GTIN (UPC or EAN) from GS1 to create a listing, unless your category or brand qualifies for a GTIN exemption. The FNSKU is then generated by Amazon for FBA labelling.

Where does the FNSKU barcode come from?

Amazon generates the FNSKU and provides a printable label (a Code 128 barcode) in Seller Central when you set up FBA. You do not invent it yourself.

Can EAN Studio give me a UPC or FNSKU?

No. The GTIN comes from GS1 and the FNSKU comes from Amazon. EAN Studio draws the barcode image and builds the label from a number you already have.