On a Receipt, What Is a UPC?

When you receive a receipt from a purchase made at any kind of store, you might find a UPC barcode. The UPC, which stands of Universal Product Code, is a type of barcode used across the world for tracking items in stores. The UPC data standard is maintained by GS1, an international standards organization.

UPC barcodes are used in many stores to improve the efficiency of the checkout process, reduce errors and provide an easier way to manage inventory. A UPC barcode can be scanned with a flat-bed or handheld barcode scanner to provide a computer system with a 12-digit inventory code, which is then linked to an individual product in the computer's database. UPC barcodes are the only barcodes allowed for trade items in the US.

Each line on the barcode represents "1" and each blank space represents "0." A computer scanning the code can interpret the pattern of lines and spaces as a string of 1s and 0s, which together comprise a binary number. For example, the first and last parts of the barcode -- known as the "Lead" and "Trailer" - are represented by a bar, a space and another bar, which represents the binary number "101."

The 12 digits of a UPC barcode are split into four parts. The first describes the type of product: for example, "0" or "7" are used for regular UPC codes, and "5" indicates a coupon. The next five digits identify the manufacturer, while the next five indicate the unique product code. The final digit is the checksum digit, which is computed from the other digits and can be used to validate the rest of the code as correct.

The nominal size of a UPC-A barcode is defined by GS1 as 1.496 inches wide and 1.02 inches high. This can be scaled by 80 percent to 200 percent, for a maximum size of 2.938 inches by 2.04 inches. A blank zone, known as the "Quite Zone," is inserted in front and behind of the barcode and is comprised of 9 blanks, or 9 zeros. Separating the manufacturer code and the product code is a pattern called the "Separator," indicated by "01010."