What's a UPC Code and How They Relate to Amazon

Understanding product identifiers is one of those unglamorous things that will save you from real headaches on Amazon. This is also the area where my original advice has changed the most, so pay attention to the 2026 update below — following the old approach today can get your listings suppressed.

What is a UPC barcode?

UPC stands for Universal Product Code. It's the familiar barcode scanned at checkout in stores, consisting of a machine-readable bar symbol and a human-readable 12-digit number. In the US and Canada you'll mostly work with UPC-A codes. Internationally you'll encounter the 13-digit EAN (European Article Number). Both are types of GTIN (Global Trade Item Number) — the umbrella term for the unique number that identifies a product.

A little history

UPC barcodes were originally conceived for grocery stores to speed up checkout and manage inventory. The first concept dates to the 1930s, the "bull's eye" method was patented in the 1950s, and on June 26, 1974 the first UPC was scanned on a pack of Wrigley's gum in Troy, Ohio. The system, developed through IBM and standardized by what became GS1, spread across retail from there.

How identifiers relate on Amazon

Here's how the pieces fit together, because the terms get confused constantly:

• GTIN — the umbrella term for the global product number. UPC and EAN are both GTINs.
• UPC / EAN — the actual barcode number you provide when creating a listing.
• ASIN — Amazon Standard Identification Number. Amazon's internal ID for a listing. When you create a listing with a UPC, Amazon assigns it an ASIN.
• FNSKU — Fulfillment Network Stock Keeping Unit. The Amazon-specific barcode you put on each physical unit you send to FBA so Amazon can track your inventory specifically.

You need a GTIN (usually a UPC) for almost every new product you list, unless your category qualifies for a GTIN exemption.

The big 2026 update: buy your barcodes from GS1, not eBay

When I first wrote this post, I suggested buying cheap UPCs in bulk from third-party resellers. Do not do that anymore. Amazon now verifies UPCs against the GS1 database. UPCs that don't match GS1's records — which is exactly what cheap reseller codes are — are treated as invalid and can lead to listing suppression, errors, and even account issues. Amazon's own guidance states that you must obtain valid UPCs directly from GS1.

What to do instead:

• License a GS1 Company Prefix through GS1 (gs1.org / gs1us.org). This gives you a prefix tied to your brand from which you can generate legitimate GTINs for all your products.
• Or obtain GTINs from the product's actual manufacturer if you're selling someone else's branded product.
• Check eligibility for a GTIN exemption if you're selling unbranded or private-label goods in a category that allows it — Amazon can let you list without a UPC in some cases.

The cost of doing this correctly is modest relative to the risk. Sellers who cut this corner have had years of work wiped out by deactivations, so treat legitimate barcodes as foundational, not optional.

Labeling your products for FBA

Once your listing exists, you label the physical units for FBA. In most cases that means applying an FNSKU label to each unit so your inventory stays separate from other sellers' (rather than commingled). This is strongly recommended for branded and private-label sellers because it protects you from being blamed for another seller's defective or counterfeit stock. Note that as of January 1, 2026, Amazon ended its in-house FBA prep and labeling service, so you (or a prep center / 3PL) are now responsible for applying these labels before inventory arrives. Labels need to be scannable, printed clearly, placed flat (not on corners or seams), and any existing manufacturer barcode should be covered.