Barcode Xpress for .NET Framework v13.9 - Updated
UPU_S18 4-State Barcode
Supported Barcode Types > Barcode Types > UPU_S18 4-State Barcode

The UPU (Universal Postage Union) S18 4-State barcode is a variable-length, alphanumeric, self-checking 1D barcode with Reed Solomon Error Correction. This barcode is used by the Universal Postage Union to route mail throughout the United Nations.

Example Barcode

The following example barcode encodes the information "J18CUSA8E6NN062315014880T" as an UPU S18 4-State barcode:

UPU S18 4-State


A UPU S18 4-State barcode is a 4-State barcode that is either 57 or 75 bars in length. There are two encoding formats for these barcodes, 18C and 18D. They each contain the following elements:

Data Element Message Representation
UPU identifier Always "J"
Format identifier Derived from the value of bits 0-3 of the binary representation. Only values 0010 and 0011 should occur.
Issuer code Determined from the value of bits 4-19 issuer code from the equipment identifier.
Equipment identifier First character: hexadecimal value (0-9; A-F) of bits 20-23. Second character: hexadecimal value of bits 24-27. Third character: hexadecimal value of bits 28-31.
Item priority Derived from the value of bits 32 and 33: bits 00 mean priority "N", 01 means "L", 10 means "H", 11 means "U".
Serial number Derived from bits 50-63 (format 18C) or 34-63 (format 18D) by conversion of the binary value to decimal and representation as a 5 (format 18C) or 12 (format 18D) digit value, with leading zeroes where necessary. Format 18C encodes the generation date and time here as well, derived from bits 34-49.
Tracking indicator Derived from the two most significant bits of the penultimate codeword of the bar code: bits 00 mean priority "T", 01 means "F", 10 means "D", 11 means "N".

Managing Organization

The Universal Postage Union manages the UPU S18 4-State specification. 1

Similar Barcode Types

Related Barcodes

UPU S18 4-State barcodes are similar to other 4-state barcodes that are common among postage organizations (e.g. Australia Post 4-State, Intelligent Mail).


  1. UPU. ID-Tagging of Letter Mail Items - Part D: 4-State Encoding Specification for Flats. Universal Postal Union, 2005.

For additional background and use-case information see our UPU 4-State barcode page.
For more information, see the Barcode Xpress SDK product page or try our online demos.

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