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Example of a POSTNET barcode Example of a USPS OneCode barcode

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About POSTNET

POSTNET is a barcode symbology used by the United States Postal Service (USPS) for encoding ZIP code information on mailpieces. Unlike other barcodes, data is encoded in the height of the bars instead of in the widths of the bars and spaces. POSTNET is a fixed dimension symbology, meaning that the height, width, and spacing of all bars must fit within exact tolerances. Most standard barcode readers cannot decode POSTNET, but it is extremely easy to print on almost any type of printer.

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Facing Identification Mark (FIM) patterns

In addition to POSTNET, the USPS also uses Facing Identification Mark (FIM) patterns, which are another type of postal barcode used in automated mail processing. FIM patterns are used for automatic facing and canceling of mail that does not contain a stamp or meter imprint (business reply mail, penalty mail, etc.). They also provide a means of separating business and courtesy reply mail from other letters. Three FIM patterns are currently in use:
  1. FIM-A is used on courtesy reply mail that has been preprinted with PostNET barcodes.
  2. FIM-B is used on business reply, penalty and franked (government) mail that is not preprinted with PostNET barcodes.
  3. FIM-C is used on business reply, penalty and franked mail that has been preprinted with PostNET barcodes.
FIM patterns are placed in the upper right corner along the top edge and two inches in from the right edge of letters and cards. If you need to create POSTNET or FIM barcodes, B-Coder Pro can help you generate them easily and accurately. B-Coder Pro is a powerful barcode generation software that supports a wide range of symbologies, including POSTNET and FIM. With B-Coder Pro, you can create high-quality barcodes for your mailpieces and streamline your barcode creation process.
Last modified on November 3, 2026