2D Barcode
Linear Barcode
Postnet barcode symbology is also known as USPS Postal Numeric Encoding Technique Barcode, Delivery Point Barocde (DPBC) and Postnet 3 of 5. POST stands for Postal Numeric Encoding Technique. Postnet barcode symbology was designed by the USPS to sort mails and encode ZIP informaiton in postal service. The Postnet barcode symbology is based and expanded by the CASS (Coding Accuracy Support System) which was invented in April 1988. Postnet barcode symbology employs 4 formats in the postal service. The first one uses 5 digit barcode (including the check digit) or 5-digit ZIP; second one uses 6 digit barcode (including the check digit); thrid one 9 digit barcode (including the check digit) or 5-digit ZIP+4 code; forth one uses 11 digit barcode (including the check digit) or 11-digit delivery point code. Postnet barcode symbology thus may composed of 32 bars, 52 bars or 62 bars. The bar height and width of postnet barcode symbology is fixed. The Postnet barcode symbology is located on the right corner or address block area of the envelope and business return mail.
Encoding Data of Postnet Barcode Symbology
Postnet barcode symbology is a numeric symbology. It is capable of encoding numeric data rangs from 0 to 9.
Component of Postnet Barcode Symbology
  • The starting frame bar (long bar) which is encoded as single 1
  • The second part is the one of the 4 formats (5, 9, or 11 data characters or ZIP) encoded in the postnet barcode
  • The following part is the checksum digit calculated automatically
  • The final frame bar which encoded as a single 1 also
Postnet Barcode Symbology is composed of 4 parts. Each set of 5 bars represents made up of one code character. 2 of the 5 bars are full bars.
How to Encode Postnet Barcode Symbology
The Postnet Barcode Symbology is expressed as the half bar (0) and full bar (1). The numberic data barcode encoded will be represted as:
Numeric data 0 is encoded as 11000
Numeric data 1 is encoded as 00011
Numeric data 2 is encoded as 00101
Numeric data 3 is encoded as 00110
Numeric data 4 is encoded as 01001
Numeric data 5 is encoded as 01010
Numeric data 6 is encoded as 01100
Numeric data 7 is encoded as 10001
Numeric data 8 is encoded as 10010
Numeric data 9 is encoded as 10100
Numeric data 2 is encoded as 00101
Checksum Calculation of Postnet Barcode Symbology
Check digit is essential for offering detection for scanning the barcode. The Postnet barcode symbology is based on the Mod10 method to compute checksum digit. The Mod10 method is utilized for verification of barcode as PC-A, UPC-E, EAN-13 and EAN-8. Note Postnet barcode symbology need not to assign odd and even position. Follow the steps to calculate the checksum digit:

Note if delivery point code and ZIP+4 being used, it should be counted.

Simply sum up all the values to get an result

Put an number to add with the result and let it be even divided by 10. The number added is the checksum digit. Like in the example, (5) +105=110. Number 5 helps number 105 to be even divided by 10. Number 5 is the checksum digit of the postnet barcode symbology.

If we want to encode (12345) in Postnet barcode symbology, the checksum digit will be calculated as (1+2+3+4+5)=15. Thus number 5 is the checksum digit of the postnet barcode symbology.