How to Read 12 Digit Barcodes?

Most bar codes in the US are 12-digit UPC (Universal Product Code) barcodes, with ten digits at the bottom of the code and one small number to each side. Impress your friends by asking them to select a random item from the kitchen with a removable label and cut the numbers off of the UPC barcode; you can then proceed to read the numbers encoded in the lines.

Reading UPC Barcodes

1. 1
   Note that barcodes are made up of both white and black lines. The white spaces in between the black lines are part of the code.
   
   
   
   

    Note that barcodes are made up of both white and black lines.
2. 2
   Understand that there are four different thicknesses to the lines. Henceforth, the skinniest line will be referred to as "1," the medium-sized line as "2," the next largest line as "3." and the thickest is "4."
   
   
   
   

    Understand that there are four different thicknesses to the lines.
3. 3
   Recognize that each UPC barcode begins and ends with 101 (thin black, thin white, thin black). In the very middle of the barcode, you will notice two thin black lines sticking down between the numbers. The thin white between them, as well as the thin whites to either side, make up a 01010. Each UPC barcode has 01010 in the middle.
   
   
   
   

    Recognize that each UPC barcode begins and ends with 101 (thin black, thin white, thin black).
4. 4
   Recognize that each digit, including the small numbers that begin and end the barcode, has its own unique four-line set. 0 = 3211, 1 = 2221, 2 = 2122, 3 = 1411, 4 = 1132, 5 = 1231, 6 = 1114, 7 = 1312, 8 = 1213, 9 = 3112. (Note that the sum of bar widths numbers is 7 for all codes because each code is 7 units wide.) Notice that the line colors are reversed after the center-line: The lines of the digits to the left are white/black/white/black whilst to the right they are black/white/black/white. This provides some error checking and allows the reader to know the direction in which it is scanning a code. It is also crucial so that the barcode ends with a bar rather than a space. So, actually, each digit has two codes.
   
   
   
   

    Recognize that each digit, including the small numbers that begin and end the barcode, has its own unique four-line set.
5. 5
   So, the barcode above whose first two digits are 03 would start out "10132111411". Broken down this is "101-3211-1411" where 101 marks the beginning of the bar code and 3211 marks the digit 0 .

=== Understanding Bar Codes ===

1. 
   
   • UPC Barcodes are typically registered and used in the United States and Canada and, therefore, do not indicate a country identifier.
   • A similar bar code system is EAN (European Article Number). It contains 13 digits and also indicates the country in which the bar code was registered. Read the first "3" digits of the code to determine this.
     • Example: If the first 3 digits of the barcode are 690, 691, or 692, the country in which the code was registered was China.
   • It is important to note that the country code in EAN bar codes does not indicate where the product was manufactured ^[1] For example, if the barcode begins with 64, then it was registered in Finland (probably to a company that was headquartered in Finland). Look more closely at the packaging, however, and you may find that the product was "Made in China".

For further reading you can go to :

 http://www.wikihow.com/Read-12-Digit-UPC-Barcodes

http://en.wikipedia.org/wiki/Barcode

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