How UPC Barcodes Work

Go take a look in your pantry or fridge, you'll see that just about everything there has a UPC barcode graphic printer on the package. In fact, almost every single product that you buy from a store has one of these barcodes on the cover.


Ever wondered what these funny looking codes are and what they're used for? In this tutorial, we'll tell you all about UPC barcodes and how you can decode them.

Universal Product Codes (UPCs) were initially invented for grocery stores to help speed up the lines at the checkout counters and also to keep track of product inventory. Due to its success, the protocol was soon adopted for all other retails products as well.

Uniform Code Council

UPC codes are assigned by the UCC (Uniform Code Council). The process of obtaining a barcode starts with manufacturers, who have to apply for a manufacturer code with the UCC. The Uniform Code Council charges manufacturers a yearly fee for being able to acquire barcodes.

Every manufacturer gets their own unique 6-digit manufacturer code that identifies them. You can easily see the manufacturer's code on the following UPC barcode which is from the back of a book...


If you look at the picture above, you see that the barcode has two parts:

1. The 12-digit human-readable UPC code
2. The black lines which are read by a barcode machine

In this example, 132013 is the manufacturer's identification code (the first 6-digits in the barcode). In the remaining UPC barcode, 70185 (the next 5 digits) is the item number. Manufacturers usually have a person in their organization called the UPC coordinator who assigns unique numbers for each item that the manufacturer makes. The UPC coordinator makes sure no two products have the same item number.

Every single item that a manufacturer makes, including variations in sizes, is given a unique item number. For example, a 1 liter bottle of Pepsi would have a different item number from a 500ml can of Pepsi.


The final remaining digit in the barcode is known as the check digit. Its main function is to ensure a barcode is scanned properly. The value of the check digit is based on the other digits in the UPC. So after doing the calculation to determine the check digit, if it doesn't match with what was read from the barcode, we can deduce the scanning was done incorrectly.

What about the price?

You might be wondering how the price is determined when you're at checkout -- since there is no price printed on a UPC barcode. What happens is that when a barcode scanner (the handheld barcode reader) scans a UPC, the system electronically sends the UPC code to the store's Point of Sale system. That system returns the price back to the cash register.

This allows the store to change prices easily -- for example when they set new sale prices. If the manufacturer printed the price on the barcode itself, the store wouldn't be able to change it to reflect their sale price.

There you have it. Now you know what UPC barcodes are and how to decode them.

For more information on barcodes, checkout Universal Product Code at Wikipedia.