FNSKU vs UPC vs EAN: Which Barcode Do You Need?
Using the wrong barcode can cause problems at receiving: Amazon's guidance says it may refuse, return, or repackage products that arrive with inadequate or non-compliant packaging, at your expense. This guide cuts through the confusion — you'll be able to work out which barcode route is likely to apply.
The 3 Barcode Types Explained
FNSKU
Fulfilment Network Stock Keeping Unit. An Amazon-generated Code-128 barcode that links a specific product to your seller account. Used by resellers on new FBA inventory, and by all sellers for products without a manufacturer barcode.
Example format:
X00ABC123D
UPC-A
Universal Product Code. 12-digit global product identifier used primarily in North America. Used to identify the product when creating or matching a listing. Amazon checks product identifiers (GTIN, EAN, UPC) against the GS1 database. Resellers use the FNSKU instead; Brand Representatives may use an eligible manufacturer barcode if the product meets Amazon's eligibility conditions.
Example format:
012345678905
EAN-13
European Article Number. 13-digit international product identifier — the UK/EU equivalent of UPC. Used to identify the product on Amazon. If you apply an FNSKU label, cover the UPC so only one barcode can be scanned. Brand Representatives may be able to use an eligible manufacturer barcode instead.
Example format:
5901234123457
Side-by-Side Comparison
Based on Amazon's guidance since 31 March 2026.
| Feature | FNSKU | UPC-A | EAN-13 |
|---|---|---|---|
| Scope | Amazon-only | North America | International |
| Digit count | 10 chars (Code-128) | 12 digits | 13 digits |
| Used as the FBA item barcode? | Yes for resellers; may be optional for eligible Brand Representatives | May be usable by eligible Brand Representatives; otherwise covered | May be usable by eligible Brand Representatives; otherwise covered |
| Used to identify the listing? | ✗ No | ✓ Yes (US/CA) | ✓ Yes (UK/EU) |
| Cost | Free | Paid (via GS1) | Paid (via GS1) |
| Generated by | Amazon Seller Central | GS1 organisation | GS1 organisation |
Understanding When You Need Each Barcode
The relationship between FNSKU, UPC, and EAN confuses many sellers because they're used at different stages of the FBA process. Here's a clear breakdown of when each one matters and why resellers can't simply substitute one for another. When you are ready to make labels, read our comparison of the best barcode generators for Amazon FBA.
Stage 1: Creating your Amazon product listing
To create a new product listing on Amazon, you need a UPC (for the US/Canada marketplace) or EAN-13 (for UK/EU). Amazon uses these to match your product to their catalogue. This is where you would use a UPC or EAN (Amazon checks product identifiers against the GS1 database), or list without one if Amazon has granted your brand a GTIN exemption. In FBA, products without a manufacturer barcode use Amazon barcodes (FNSKU labels).
Once your listing exists, Amazon assigns an ASIN (Amazon Standard ID) and an FNSKU to each product variation in your account. For resellers, the FNSKU is what you put on the physical item.
Stage 2: Labelling physical items for FBA
When you send inventory to an Amazon fulfilment centre, each item needs a barcode that Amazon can scan when they receive it. For resellers, this is the FNSKU — not the UPC or EAN. The FNSKU tells Amazon exactly who owns this inventory (your account), which listing it belongs to, and which warehouse location to route it to.
When you use an FNSKU label, cover the original UPC/EAN so it can't be scanned by mistake. If both are visible, the scanner may read the wrong one.
Source: Amazon Seller Central — FBA product barcode requirements. Since 31 March 2026, Amazon's guidance indicates resellers use Amazon barcodes (FNSKU labels) on new FBA inventory. Brand Representatives may be able to use a manufacturer barcode if the product meets Amazon's eligibility conditions.
The exception: brand owners using manufacturer barcodes
Brand owners who hold the Brand Representative role in Amazon Brand Registry may be able to use an eligible manufacturer barcode (UPC, EAN or ISBN) instead of applying an FNSKU label, if the product also meets Amazon's eligibility conditions: new condition, a single scannable barcode matching a single ASIN, and not in certain categories unless Amazon has granted an exemption through Brand Registry. Since 31 March 2026, Amazon's guidance indicates that resellers — including authorised resellers — use Amazon barcodes on new FBA inventory. If you're unsure which applies, an Amazon barcode is the conservative choice: check your route.
FNSKU vs UPC vs EAN — FAQ
Usually not, if you are a reseller. Since 31 March 2026, Amazon's guidance indicates that resellers use Amazon barcodes (FNSKU labels) on new FBA inventory, even when the product already has an EAN or UPC. Brand owners with the Brand Representative role in Brand Registry may be able to use an eligible manufacturer barcode instead, if the product meets Amazon's eligibility conditions (such as new condition and a single scannable barcode matching a single ASIN). When you apply an FNSKU label, cover the original EAN/UPC so only one barcode can be scanned. Not sure which applies? Use the FBA Barcode Checker.
Log in to Seller Central → Manage Inventory → find your product → click "Print item labels." The FNSKU is displayed on the label and also visible in the product detail within Seller Central. Amazon assigns the FNSKU; copy it exactly as shown in Seller Central (for example X00ABC123D).
Yes. Each ASIN variation gets its own FNSKU. A red T-shirt in size Small has a different FNSKU from the same shirt in Medium or Blue. This is how Amazon tracks mixed-variation inventory at the unit level in their fulfilment centres.
Ready to Generate Your FNSKU Labels?
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