Amazon Barcode Generator Guide: UPC, EAN, FNSKU and What Sellers Need to Know

Amazon distinguishes between the product identifier and the fulfillment label. The product identifier is a GTIN — UPC in the US, EAN elsewhere — used to create the listing and to sell the item through any retail channel. The FNSKU is Amazon’s own identifier for FBA inventory; it is printed on the unit label and is what the warehouse scans when your stock is received and picked.

If you sell a branded product that already has a GTIN, you can often use manufacturer barcodes instead of FNSKU labels, provided the listing is set up for commingled or manufacturer barcode tracking. For most private-label sellers, FNSKU labels are required because they tie the unit to your seller account. Never cover the original GTIN with a sticker unless the listing instructions explicitly allow it.

Cartons have separate rules. Amazon requires a carton label with the shipment ID and box number, and for pallet shipments an SSCC-compatible label. The unit barcode must not be used as the carton label. Keep the labels on the outside of the box, flat and unscuffed, and do not place them over seams or tape.

Print at a size that a warehouse scanner can read from a distance, use black bars on white, and verify a sample before sending inventory. If a shipment is rejected for unreadable labels, the cost is not just the reprint — it is the delayed stock and the investigation. A quick scan test with a phone or handheld scanner catches most problems.