UPC

The Universal Product Code (UPC) is a barcode used to identify retail items in North America and elsewhere. The most common form, UPC-A, encodes a 12-digit numeric code readable by scanners at point of sale.

It was developed in the 1970s by U.S. manufacturers and retailers and is now administered by GS1, the global standard organization. UPCs are part of the Global Trade Item Number (GTIN) system used to identify products across supply chains.

UPC-A encodes 12 digits: a leading number system digit, a five-digit manufacturer code, a five-digit product code, and a final check digit. The check digit is calculated so that the weighted sum (digits in odd positions ×3 plus digits in even positions) modulo 10 equals zero; the check digit makes the total a multiple of 10. The barcode encodes these digits as patterns of bars and spaces.

For small items, UPC-E compresses the same data into six digits and can be expanded back to UPC-A. In many markets, UPC data is compatible with the international EAN/GTIN system, often via a leading zero in front of UPC-A to form an EAN-13.

In practice, UPCs enable fast checkout, automatic price lookup, and integrated inventory and analytics across retailers and manufacturers. They form a foundational element of modern retail data systems and supply chains.