Japan Post 4-State Customer Barcode

The Japan Post 4-State Customer Barcode is the postal symbology used by Japan Post to encode postal codes and address information on mail, letters, and postcards, using the same four-state height-modulated bar approach pioneered for postal automation to enable high-speed mechanical sorting.

Japan operates a highly automated mail-sorting infrastructure, and the Customer Barcode exists to let Japan Post's mechanical sorting equipment read a mail piece's postal code and remaining address details directly from a printed barcode rather than relying purely on optical character recognition of handwritten or printed addresses. It typically appears in a designated printing zone on the envelope or postcard, most often generated automatically by postal software, word processors, or address-printing systems used by businesses and individuals for bulk or regular mail.

Like other modern postal barcodes designed around the same underlying concept, the Japan Post barcode uses four distinct bar states rather than a simple two-state (present/absent) pattern: bars can be tall (spanning the full height), or shortened from the top, bottom, or both, relative to a baseline. This four-state approach, conceptually related to the encoding principle also used in the USPS Intelligent Mail Barcode and the Dutch KIX Code (both covered elsewhere on this site), allows each bar position to carry more information than a simple binary bar/space code, packing postal code and address-block data into a compact printed strip suitable for standard envelope and postcard formats.

• The Japanese postal code (yūbin bangō), typically seven digits, identifying the delivery post office and local area.
• Additional address-block information beyond the bare postal code, assisting automated sorting equipment in routing mail to a more specific delivery point.
• A check character or checksum structure validating the encoded digits before automated routing decisions are made.

The Japan Post barcode shares its conceptual four-state height-modulation approach with the USPS Intelligent Mail Barcode and the Dutch KIX Code, both covered elsewhere on this site, though each is an independently defined national standard with its own field structure, check digit method, and printing specification — they are not mutually interoperable or interchangeable despite the shared underlying idea of encoding more than one bit per bar position. Where the Royal Mail RM4SCC (also covered on this site) similarly uses four bar states for UK mail, the Japan Post barcode is specific to Japan Post's own postal code format and sorting infrastructure.

Because the barcode is read by dedicated Japan Post sorting machinery rather than general-purpose retail scanners, businesses and mailers in Japan typically generate it through certified postal software or printing services rather than implementing the encoding from scratch, ensuring correct placement within the designated barcode zone on the envelope and correct address-to-postal-code mapping. Print position and orientation matter significantly, since automated sorting equipment expects the barcode within a specific zone relative to the address block on standard Japanese envelope and postcard formats.