Decode one
Scan or paste a barcode and see every part of it.
Make one
Generate a valid barcode from fields.
Where you’ll see it
- Older UK business mail, printed near the address.
- Less and less. Royal Mail no longer offers it for its Retail and Network Access services, which now use Mailmark barcodes instead.
Anatomy
Each bar is in one of four states:
Each character is four bars: two that reach up and two that reach down. That gives 36 characters, the digits 0 to 9 and the letters A to Z.
Checksum
The last character before the stop bar is a checksum, calculated from the upper and lower halves of all the other characters. Scanners verify it and drop it.Variants and related types
- Royal Mail Mailmark: the barcode that replaced it, which looks similar but carries more and has error correction.
- KIX: the same bars, without start and stop bars or a checksum, used in the Netherlands.
Scanning it in your app
Specification
- Royal Mail Mailmark barcode definition: confirms that the Customer Barcode is no longer available for Retail and Network Access services.
- Seagull Scientific barcode guide: a secondary description of the 4-state customer code and its Dutch variant.