How UPC barcodes work.

Look at just about every product that you have purchased from a store and you will see a UPC barcode. The majority of barcodes are 12 digit barcodes called UPC-A barcodes. The barcode is comprised of a series of bars - the machine readable portion of the barcode and the numbers below them. This is called the human readable portion of the barcode.

Barcodes are really less sophisticated than people think

UPC stands for Universal Product Code. Originally created to help grocery stores be more efficient in their check out process, they have moved to all other retail products because they worked so well.

Universal Product Codes (UPCs) start with an organization called GS1. They were formerly called the Uniform Code Council (UCC). A manufacturer applies for permission and a subscription with GS1 for the privilege to use barcodes. The manufacturer pays an annual fee for the ability to use UPC barcodes.

The GS1 then issues the manufacturer a six-digit manufacturer identification number. This allows the manufacturer to generate an barcodes based on the numbers available.

What do all the numbers in a barcode mean?

Let's use the following number as an example: 753182000008

The manufacturer identification number is the first six digits of the UPC number -- 753182 in the example above. The next five digits are the item number (00000). The company assigns one person in their company to act as a UPC coordinator assigning UPC item number, making sure numbersa are not duplicated, and retiring codes that are assigned to products that have been discontinued.

The last digit in the bar code is called a check digit. The check digit is a mathematical equation adding and multiplying different digits together. At the end of this tutorial, we will discuss how a check ditit is determined.

Every item needs its own barcode, including items that are combined.The best example is Coca-Cola. A 12 ounce can needs a barcode, as does a 12 ounce bottle, 16 ounce bottle and litre bottle. When the cans are bottles are combined to make a new product (a six-pack, 12 pack, etc.) these new products need a unique barcode.

There is no data embedded in a UPC barcode other than the number itself. There are no price codes, there is no description or inventory information...just the number.

The barcode represents the series of numbers assigned to the product by the manufacturer. When the product is sold to a retailer by a wholesaler, the retailer takes the information sheet and inputs the data into their computer system for their store or group of chain stores. The will input the name of the item, manufacturer or wholesaler, product description and price. Stores may add other information as pertaining to the item such as color, size, weight, etc. to help them identify the product. In addition to all of this information, beginning and updated inventory counts are input into the computer system.

The computer system is networked to the electronic cash registers (also called point of sale systems). The cash registers can access all of the data from the main computer system.

When the customer takes the item to the checkout counter, the clerk scans the item, information is pulled from the network and the customer is charged for the item. At the same time, the purchased item is deleted from inventory allowing for an accurate inventory count.

We recommend a two ways to purchase a genuine UPC bar code.
If you are a large manufacturer who needs thousands of UPC barcode, you can go directly to the GS1 http://www.gs1.org/

If you only need one, or a few hundred barcodes, you might want to consider Nationwide Barcode. http://www.nationwidebarcode.com

How to determine the check digit on a barcode

1. The last digit of the UPC code is called a check digit. This digit lets the scanner determine if it scanned the number correctly or not.

2. Add together the value of all of the digits in odd positions
(digits 1, 3, 5, 7, 9 and 11).

3. Multiply that number by 3.

4. Add together the value of all of the digits in even positions
(digits 2, 4, 6, 8 and 10).

5. Add this sum to the value in step 2.

6. Take the number in Step 4. To create the check digit, determine the number that, when added to the number in step 4, is a multiple of 10.