Barcode Check Digits

Check digits verify that the embedded barcode data is decoded correctly by the host system. The check digit is calculated from all the data characters in the barcode.

• Not all symbologies have a check digit - e.g. D2 of 5 doesn't
  
  
  
• Some symbologies give the option to include a check digit or not - e.g. Code 39
  
  
  
• In some symbologies the check digit is automatically embedded in the barcode - e.g. UPC A