how to calculate the upc checkdigit
All UPC barcodes have a checkdigit. The UPC checkdigit is the last digit in the lower-right corner of a UPC A or UPC E bar code. The checkdigit provides error correction by insuring that a barcode scanner correctly decodes a UPC symbol.
The 12th digit of a UPC barcode is thea checkdigit which is based on the preceeding 11 numbers. The first 11 digits in a UPC barcode are unique to each product. It's a combination of the manufacturer's number plus the specific item's number.
Take for example the barcode "69277198116". Let's see how the checkdigit is calculated for this UPC barcode.
Begin by adding up all the digits in the odd positions from left to right. Multiple the result times 3. Now add up the digits in the even positions. Add the first subtotal to the second subtotal. That UPC number's checkdigit is the single digit number makes the total a multiple of 10.
6+2+7+9+1+6=31 31x3=93 9+7+1+8+1=26 93+26=129 and 1 makes 130.
That means 1 is the checkdigit for 69277198116: 692771981161
UPCTools is a font collection available for Windows and OS X that prints UPC, ISBN-13, EAN, and JAN barcodes in your favorite applications. And yes, UPCTools calculates the UPC checkdigit for you!
