UPC Barcodes Explained: How UPC Codes Work on Product Labels

Updated for 2026: Understanding how UPC barcodes work on product labels and retail packaging.

Many product brands want the look of a barcode on their packaging or hangtags, but not everyone understands how a UPC barcode actually works.

What Is a UPC Barcode?

A UPC barcode (Universal Product Code) is the standard barcode used on retail product labels throughout the United States. These barcodes allow retailers to track inventory, scan products at checkout, and manage pricing quickly and accurately.

How Do UPC Barcodes Work?

A UPC barcode, specifically the UPC-A format (Universal Product Code), is the most common barcode used in the United States. It is also called a GTIN (Global Trade Item Number). A UPC-A is comprised of 12 digits. The digits in a UPC barcode represent the manufacturer and the item itself. The first few digits of a barcode are called the Block ID number or GS1 company prefix. They function like a license plate for your product — unique to your company and not shared with anyone else. The rest of the digits (except the last digit) are for your item. The best advice is to start a spreadsheet with the numbers and what they equal. If you’re just getting started, our guide to getting started with UPC codes walks through the process step-by-step. The last digit is called a check digit. It’s generated by a mathematical calculation based on the first 11 digits. It’s not something you can add. An actual barcode can be created once you have all 12 digits. That’s where we come in. We have the software and printers to generate barcoded tags and labels for your items.

For new or smaller clients wanting to create a custom hangtag and are not sure of how to incorporate a barcode, my advice is to create a tag that has your artwork on the front and then leave space on the back side for a barcode, retail price, style number, etc….

Once your goods are sold to a retailer they will typically require a UPC barcode on the items. We can print an additional sticker with the variable information and stick it on the back. It will allow you to order less of the hangtags without having to stock tags for every single item. For large manufacturers, the barcode and other variable data can be imprinted at the same time your custom tag is created.

We can also print other types of barcodes on clothing labels. QR (quick response) codes are becoming very popular and can be used effectively on our one color printed labels. Read more about them here. We can offer woven cloth labels with a barcode for appearance only. A barcode is too sensitive to be woven and made to scan effectively.

Links

To obtain a GS1 company prefix visit http://www.gs1us.org/get-started/i-need-a-gs1-company-prefix

To use a check digit calculator visit:

http://www.gs1us.org/resources/tools/check-digit-calculator