UPC (Universal Product Code) is a retail barcode used to uniquely identify a product and its manufacturer. It is used at departmental stores and other POS in the USA , Australia, and United Kingdom.
When people speak of UPC barcodes, they are usually referring to the UPC-A or UPC-E barcode symbologies.
UPCA is a 12 digit code. The first six digits represent the number system character and the manufacturer of the labeled item, while the next five digits are a unique product identifier. The last digit is a check character that is derived from the previous 11 digits of data.
A typical UPCA barcode has center guard bars which divides the symbol into the left and right half. This division allows the symbol to be read in any orientation.
In the example above, 012345 refers to the number system and manufacterer, while 67890 is the product identifer. The digit 5 is the check digit.
UPC-E (also known as the "zero suppression version") is a variant of the UPC barcode used for small items. The symbol enables manufacturers to encode 12-digit product codes with just six digits. This is made possible by using an algorithm to convert the 12-digit value to its 6-digit equivalent.
Not all UPC-A values can be converted to UPC-E, but only those with several zeros in between.
Conversion of UPC-A barcode to UPC-E
(i) If the manufacturer code ends in 000, 100, or 200, the UPC-E barcode will be made up of the first two characters of the manufacturer code and the last three characters of the product code, followed by the third character of the manufacturer code. The product code must be in the range 00000 to 00999.
(ii) If the manufacturer code ends in 00 but does not qualify for the first point above, the UPC-E barcode code consists of the first three characters of the manufacturer code, the last two characters of the product code, followed by the digit "3". The product code must be in the range 00000 to 00099.
(iii) If the manufacturer code ends in 0 but does not quality for the first point or second point above, the UPC-E barcode consists of the first four characters of the manufacturer code, the last character of the product code, followed by the digit "4". The product code must be in the range 00000 to 00009.
(iv) If the manufacturer code does not end in zero, the UPC E barcode consists of the entire manufacturer code and the last digit of the product code. Note that the last digit of the product code must be in the range of 5 through 9. The product code must be in the range 00005 to 00009.
The six digits of UPC-E are enclosed within two guard bars on the left and three guard bars on the right. The check character is encoded using the character set pattern of the six data digits.
In the above example, the UPC-E barcode with the value 425261 is converted from the UPC-A 042100005264.
The first 6 digits (042100) end with 100, and the next 5 digits (the product code) are 00526. So according to the rule (i) above, the UPC-E will be 42 526 1.