Postnet

The Postnet (Postal Numeric Encoding Technique) is a fixed length symbology (5, 6, 9, or 11 characters) that uses constant bar and space width. Information is encoded by varying the bar height between the two values. Postnet bar codes are placed on the lower right of envelopes or postcards, and they are used to expedite the processing of mail with automatic equipment and provide reduced postage rates.

A Postnet code consists of the following elements:

  • A tall start bar.
  • Data digits consisting of groups of five bars for each digit to be encoded. Each digit contains two tall bars and three short bars.
  • A five bar check character. The value of the check digit is chosen such that the sum of all data digits and the check character is an integral multiple of ten.
  • A tall stop bar.

Note Postnet cannot be used in combination with any other bar code type when specifying multiple bar code types. Also, only one Postnet bar code can be recognized per page.

A sample Postnet code is shown here.


Postnet bar code