What Is UPC?
Definition
UPC (Universal Product Code) is a barcode family used especially in US and Canadian retail. It was first deployed in grocery stores in the 1970s for checkout automation and is historically the first large-scale application of barcodes.
Its most common variant is UPC-A with 12 digits; that number is identical to GTIN-12. UPC-E is a compressed variant designed for small products.
To check a UPC-A number, use the UPC checker.
UPC-A structure
UPC-A has 12 digits: a number system digit, a company prefix and item number, and a trailing check digit. The first digit (number system) signals the number's usage context.
For example, the number system digit 0 is used for most general products, 2 for variable-weight items weighed in store, and 3 for drug and health products. This digit shows the product's category, not ownership.
The check digit is computed with the GS1 modulo-10 method using weights 3 and 1, the same logic as EAN-13.
UPC-E
UPC-E is a 6-8 digit form of UPC-A shortened with a zero-suppression technique. UPC-A numbers that contain zeros in certain positions can be expressed with a shorter barcode by dropping those zeros.
This variant is designed for small products with tight packaging, such as pens, lipstick or gum. A UPC-E can be expanded back to a 12-digit UPC-A according to a standard rule.
When validating, a UPC-E must first be converted to its expanded 12-digit form; the check digit is evaluated on that full form.
Relationship to EAN
A UPC-A can be represented as a valid EAN-13/GTIN-13 by adding a leading 0. That's why modern systems usually store UPC and EAN together in the same GTIN field.
UPC and EAN began as separate systems in the 1970s and were made compatible over time under the GS1 umbrella. Today a scanner in a European store can read an American UPC too.
To evaluate both types in one structure, see the GTIN validator, and for an EAN-13 comparison, what is EAN-13.
When it's used
UPC is the natural choice for businesses selling primarily in the North American market, whose retail systems are accustomed to the format. But because it's compatible with EAN-13, it causes no issues for global sales.
To produce a print-ready UPC-A image, use the barcode generator. Remember that for retail the number must be registered and unique.
For products too small to fit UPC-A, short forms like UPC-E or EAN-8 are considered.
Important limit
Creating a UPC with a valid check digit does not mean the number is registered to a real product. The check digit only verifies technical consistency.
Selling in North American retail requires a unique, registered UPC/GTIN, obtained by applying to GS1 (GS1 US in the US). This site does not assign official numbers.
To check whether a number is registered, use GS1's official verification services.