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What Is an FNSKU?

FNSKU (Fulfillment Network Stock Keeping Unit) is Amazon's internal barcode for FBA inventory. It links a specific product to a specific seller's account — unlike a UPC, which identifies the product universally. When you send inventory to an Amazon FBA warehouse, each unit must be labeled with either an FNSKU or the manufacturer's standard UPC.

Real example

If you and a competitor both sell the same product with the same UPC (say, a glass water bottle), Amazon's commingled inventory system might mix your units together. With FNSKU labeling, your specific units are tracked to your seller account separately — preventing commingling and potential returns of another seller's damaged goods.

How an FNSKU is used in e-commerce

  • Amazon FBA requires FNSKU labels on units when you opt out of commingled inventory (Stickerless).
  • If you opt into Amazon's Transparency program (anti-counterfeiting), each unit gets a unique FNSKU.
  • FBA prep services apply FNSKU labels on your behalf when they receive inventory.
  • The FNSKU for a product is found in Seller Central under the product's SKU settings.

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UPC codeGTINASINUPC for Amazon FBA