Aztec Code
A compact matrix code with a bullseye finder and no quiet zone — popular on rail tickets.
Aztec Code Specification
| Character set | Numeric, alphanumeric (upper and lower case), byte, and digit-pair compaction modes |
| Data length | Up to 3,832 numeric / 3,067 alphanumeric / 1,914 bytes (full range) |
| Check digit | No check digit; Reed-Solomon correction selectable in 23 steps (~5%-95%) |
| Density | Comparable to QR Code at equal size; higher usable density due to zero quiet zone |
| Module width (X-dimension) | 0.30-0.50 mm typical for print; excellent performance on screens |
| Print ratio | Square grid of uniform modules |
| Magnification | Compact symbols from 15×15; full-range up to 151×151 modules |
| Quiet zone | None required — the only major symbology with a true zero quiet zone |
| Standard | ISO/IEC 24778; AIM USS Aztec Code |
| Origin | Andrew Longacre Jr., Welch Allyn, 1995 |
| Sample data | This is Aztec Code |
Try It: Generate a Aztec Code Barcode
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What Is Aztec Code?
Aztec Code, standardized as ISO/IEC 24778, is a 2D matrix symbology built around a square bullseye finder at the center with data spiraling outward. The distinctive design eliminates the quiet zone entirely — the finder pattern and orientation marks are internal — and the grid starts as small as 15×15 modules (compact mode). Full-range symbols scale up to 151×151 modules carrying up to 3,832 digits or 1,914 bytes.
Error correction is unusually tunable: 23 selectable levels from roughly 5% to 95% of the symbol, so an implementer can trade capacity for robustness precisely. Aztec found its home in rail and transit ticketing (SNCF, Deutsche Bahn, and many national railways print it on tickets and phone screens), government registration documents, and tickets scanned from backlit displays — where its lack of quiet-zone margins and tolerance for low contrast shine.
Common Applications
- Railway and transit tickets (print and mobile screen)
- Government vehicle registration and permits
- Airline crew and airline industry documentation
- Tickets scanned from backlit phone displays
Related Barcode Types
The dominant 2D matrix barcode: up to 7,089 digits in a square symbol with selectable error correction.
A compact 2D matrix code with fixed Reed-Solomon error correction — the standard for pharma serialization and tiny parts.
A stacked-linear 2D code carrying up to 1,850 text characters — the workhorse of IDs, boarding passes, and transport documents.
Aztec Code FAQ
Why does Aztec Code need no quiet zone?
The central bullseye and the mode message ring around it are self-locating: a decoder finds the target, reads orientation and layer count from the ring, and then samples outward. Because locating does not depend on detecting an empty margin, the symbol can butt directly against other print — a real advantage on crowded tickets.
What is the difference between compact and full-range Aztec?
Compact Aztec (1-2 data layers around the bullseye, up to ~108 bytes) is for short strings and is instantly recognizable as a tight spiral. Full-range Aztec adds a grid of reference patterns every 16 modules, scaling to 32 layers and thousands of characters. Most ticket data falls in between, using mid-size full-range symbols.