UPC Code

The Universal Product Code was the first barcode standard adopted for retail, introduced in the United States in the 1970s. The familiar UPC-A symbol you see on packaging encodes a 12-digit number that uniquely identifies a single product variant. When a cashier scans it, the register looks up that number to find the price and product details.

A UPC is built from three parts: a GS1 company prefix that identifies the brand owner, a product reference number assigned by that brand, and a final check digit calculated from the other eleven. Because the company prefix is licensed uniquely to one business, no two companies can issue the same UPC, which is what makes it reliable for retailers and marketplaces.

It is important to remember that the UPC is the number, not the bars. The striped symbol is just a machine-readable way of printing that number. The same 12-digit UPC can be typed directly into a marketplace listing form without any barcode image at all.

These terms describe the same family of identifiers at different lengths. GTIN is the umbrella standard. A UPC is a GTIN-12 (12 digits, North America). An EAN-13 is a GTIN-13 (13 digits, used in Europe and most of the world). They are not competing systems — they are formats of one global standard managed by GS1.

This matters in practice when you sell across regions. A North American product with a UPC can be listed on a European marketplace that asks for an EAN: you add a leading zero to convert the 12-digit UPC into a 13-digit GTIN-13. The underlying GS1 prefix and check logic remain valid, so the number still resolves to the same product.

Genuine UPCs come from GS1, the global standards body, or its US member organisation GS1 US. You license a company prefix, pay a fee based on how many product numbers you need, and then assign UPCs to your own products and calculate their check digits.

If you resell branded products, the manufacturer has already assigned a UPC and printed it on the packaging — you reuse that number rather than buying your own. If you sell private-label or own-brand goods, you need your own GS1 prefix so the UPCs are registered to you. Avoid cheap resold or recycled UPCs from third-party sellers, because Amazon and other marketplaces validate codes against the GS1 database and reject barcodes that are not registered to your brand.