Azalea Software, Inc. www.azalea.com UPC Check Digit Calculation

UPC barcode software

A check digit (also called a ‘check sum’) is used to assure accuracy; to “check” for errors. In general check digits are a single digit computed from the other characters in the string. The digit in the lower-right corner of a UPC barcode is the UPC check digit.

All UPC (Universal Product Code) bar codes include a modulo-10 check digit. In the example on the left, the "1" is the check digit. The UPC check digit is the twelfth digit, located to the far right of the UPC number. The first 11 digits in a UPC barcode are the assigned manufacturer's number and the manufacturer assigned product number. The 12th and final digit is the UPC check digit.

Calculating the UPC check digit involves an unusual algorithm. The easiest way to figure out a UPC check digit is to use our free Excel spreadsheet. It is possible to work it through on paper.

Want to give it a try? Grab a pencil!

Our example barcode data is 69277198116.

  1. dd the digits in the odd-numbered positions (first, third, fifth, etc.) together and multiply the total by three.
    6+2+7+9+1+6=31   31x3=93
  2. Add the digits in the even-numbered positions (second, fourth, sixth, etc.).
    9+7+1+8+1=26
  3. Add the two results together.
    93+26=119
  4. Now what single digit number makes the total a multiple of 10? That’s the check digit.
    119 plus 1 makes 120

1 is the checkdigit for 69277198116:   692771981161

buy UPC barcode softwareUPCTools 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 check digit for you!