Royal Dutch KIX Generator

What Is a KIX Code?

KIX (short for Klant Index, or "customer index") is a postal barcode developed for use by the Dutch postal service, historically under the TNT Post brand and now operated as PostNL. It's a four-state symbology — meaning each bar can appear in one of four vertical positions (full-height, ascender, descender, or tracker-only) rather than simply being present or absent — which packs more information into a shorter horizontal run than a traditional two-state barcode like Code 39.

KIX was built specifically for automated mail sortation in the Netherlands. Unlike many national postal codes, it does not include a checksum digit. That's a deliberate design tradeoff: the format favors compactness and encoding simplicity over built-in error detection, relying instead on the postal system's downstream processes to catch misreads.

How KIX Encodes Data

Each character in a KIX code — digits 0–9 and letters A–Z — maps to one of the four bar-height patterns, with each character represented as a unique combination of two tall bars and two short bars arranged across the four available track positions. A typical Dutch KIX code encodes the postcode (four digits plus two letters, e.g. 1234AB) followed by a house number and, optionally, a house number addition (like an apartment or suite letter). There's no explicit start/stop pattern beyond the fixed structure of the input itself, and because there is no check digit, the exact string you type is exactly what gets encoded — accuracy on input matters more here than with checksum-protected postal codes.

Technical Specifications

A KIX code accepts alphanumeric input — digits 0–9 and uppercase letters A–Z — with each character mapped to its own four-state bar pattern. There's no fixed total length in the way EAN-13 or ITF-14 are fixed at a specific digit count; a KIX string is simply as long as the postcode, house number, and optional addition require, typically somewhere around 9–13 characters for a standard Dutch address. Because KIX carries no check digit at all, the format offers no built-in mechanism to detect a transposed digit or dropped character — this is the single most important technical fact to know before using it for anything beyond internal testing.

Where KIX Codes Are Used

KIX is specific to Dutch mail handling:

• PostNL mail sortation — printed directly on envelopes and parcels to let automated sorting equipment route mail by postcode and address without OCR.
• Direct mail and bulk mailing — Dutch businesses sending large mailings print KIX codes to qualify for postal discounts tied to machine-sortable mail.
• Return envelopes and reply mail — pre-printed KIX codes on Dutch business reply mail speed up return sorting.
• Logistics and courier labels — some Netherlands-based parcel services still reference KIX-style postcode encoding on interim sortation labels.

How to Create a KIX Code in Barcode Mint

Select Royal Dutch KIX from the Postal Code group in the symbology list. Enter the Dutch postcode and house number as a single string, following the standard 1234ABhousenumber pattern — the live preview updates immediately so you can confirm the bar pattern matches your input before exporting. Because KIX has no check digit, double-check your postcode and house number against the actual address before printing; the generator will faithfully encode whatever you type, including typos.

• Adjust bar height and spacing to fit your envelope's designated barcode zone — Dutch mail specifications define a specific placement area on the envelope face.
• Set foreground color to solid black; postal scanners are tuned for high-contrast black-on-white and don't reliably read colored or reversed-contrast bars.
• Export as PNG or SVG for insertion into mail-merge templates, or use Copy to drop the code directly into a document layout.
• Use the bulk CSV → ZIP/PDF tool to generate a unique KIX code for every recipient in a mailing list in one pass.
• Call the REST API — /barcode?type=kix&data=1234ABhousenumber — to generate KIX codes on demand from a mail-merge or fulfillment system.

Print and Scan Best Practices

KIX codes are read by high-speed sorting equipment, so print quality and placement matter more than aesthetics:

• Place the code in the designated barcode zone specified by PostNL's mailing guidelines — sorting machines expect it in a consistent location on the envelope.
• Print in solid black ink on a light background; avoid textured or glossy stock that can scatter the scanner's light source.
• Keep the barcode's quiet zone (margin) clear of address text, logos, or other print that could be misread as part of the code.
• Since there's no check digit, validate your postcode and house number data before a large mail run — a single wrong character routes that piece incorrectly with no automatic error flag.
• Test a printed sample at actual size before committing to a full mailing; scaling errors are a common cause of misreads with four-state postal barcodes.

KIX vs Other Postal Barcodes

KIX belongs to the same broad family of four-state postal symbologies as Australia Post's 4-State Customer Barcode and Japan Post's barcode — all three use the same tall/ascender/descender/tracker bar-height technique to pack address data into a compact strip. Where they differ is checksum design and alphabet: KIX has no check digit at all and accepts full alphanumeric input for Dutch postcodes, while Australia Post and Japan Post both build in checksum-style validation over primarily numeric routing data. Compared to Deutsche Post's Identcode and Leitcode — which are numeric, checksum-protected, and built on Interleaved 2 of 5 rather than a four-state structure — KIX is simpler to encode but offers no automatic error detection, which is why input accuracy matters more with KIX than with almost any other postal code in this category.

Common uses

• PostNL automated mail sortation on envelopes and parcels
• Dutch direct mail campaigns qualifying for machine-sortable postage discounts
• Business reply mail and pre-paid return envelopes in the Netherlands
• Mail-merge systems printing personalized KIX codes per recipient
• Netherlands courier and logistics interim sortation labels

Frequently asked questions

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