Amazon FBA Barcode Requirements

Selling on Amazon FBA needs two barcodes: a GS1-registered UPC for the listing, and an FNSKU label on every unit you ship in. Here's exactly what each is, the label specs, and how to generate them free.

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1. The UPC (listing identifier)

A 12-digit GS1-registered UPC-A goes in the listing's Product ID field. Amazon verifies it against the GS1 database — it must resolve to your brand. Generate UPC-A for testing, or buy a real one from GS1 for live listings.

2. The FNSKU label (per unit)

Amazon assigns an X00-prefixed FNSKU in Seller Central. You print it as a Code 128 label on every physical unit shipped to FBA. Render an FNSKU label from the code Amazon gave you.

Amazon FBA barcode FAQ

What barcode do I need for Amazon FBA?

Two. A GS1-registered UPC-A (or EAN-13 outside North America) as the product's external identifier in the listing, plus an FNSKU label on every physical unit you ship to Amazon's fulfillment centers. The UPC identifies the product; the FNSKU identifies your specific inventory inside Amazon's warehouse.

What is an FNSKU label?

FNSKU (Fulfillment Network Stock Keeping Unit) is Amazon's per-unit barcode for FBA. It's a Code 128 barcode starting with 'X00' that Amazon generates in Seller Central. You print it and stick one on every unit so Amazon tracks your inventory separately from commingled stock. You don't generate the FNSKU number yourself — Amazon assigns it; you render and print the label.

Do I need a real GS1 UPC for Amazon FBA?

For most categories, yes. Since 2021 Amazon verifies UPCs against the GS1 GEPIR database; codes from resellers that resolve to someone else's company name get rejected. Buy directly from GS1 (gs1us.org, $30 for one GTIN, no annual fee). The exception is GTIN Exemption — approved for handmade, bundles, and certain private-label cases.

What size should an FNSKU label be?

Amazon requires 1" x 2" to 2" x 3" labels (Avery 5160 / 5163 are common). Code 128 at minimum 6pt human-readable text, printed at ≥300 DPI on a thermal or laser printer. The label must cover the manufacturer's original barcode so it doesn't double-scan.

What is GTIN Exemption on Amazon?

If you sell handmade goods, bundles, or private-label products without a manufacturer barcode, Amazon may grant a GTIN Exemption so you can list without a UPC. You still need FNSKU labels on FBA units. Apply in Seller Central under Catalog → Add Products → GTIN Exemption; most rejections are due to brand-name mismatch on the application.