You need a unique UPC for every "SKU." If you sell a shirt in 3 sizes and 2 colors, you need 6 unique UPC codes.
GS1 is the global organization that sets the standards for barcodes. When you buy from them, you get a Company Prefix that identifies your brand. This is the gold standard and is required by many major retailers (like Walmart, Target, and increasingly, Amazon). buy upc codes online
These companies bought bulk quantities of UPC prefixes years ago (before GS1 changed its licensing rules) and sell individual codes to small businesses. They are much cheaper but come with some risks regarding retail acceptance. 2. Where to Buy You need a unique UPC for every "SKU