// Key takeaways
- GS1 DataMatrix and plain Data Matrix look the same; the difference is the FNC1 and the GS1 data rules inside.
- A GTIN, expiry date and short batch fit in an 18 × 18 symbol, about 9 mm square at the GS1 target module size.
- On retail items GS1 sets a module size of 0.396 to 0.990 mm and a 1-module quiet zone, in addition to the linear barcode.
- Reading needs a 2D imaging reader or smart camera; laser scanners and linear imagers cannot read it.
- Direct part marks on metal are a related but different job, with their own lighting and grading.
What makes a Data Matrix a GS1 DataMatrix?
A GS1 DataMatrix is the ECC 200 version of Data Matrix, the only version that supports GS1 element strings. It begins with an FNC1 character, which marks it as carrying GS1 data, and separates variable-length fields with FNC1 or the group separator character <GS> (GS1 General Specifications, 5.6.2). A reader reports it with its own symbology identifier, ]d2, so the receiving system knows to parse GS1 Application Identifiers. GS1 publishes a guideline on its use (GS1 DataMatrix Guideline).
| Code | What it carries | Who can read the meaning | How it is applied |
|---|---|---|---|
| GS1 DataMatrix | GS1 Application Identifiers after a leading FNC1 | Receiving and retail systems can split the data into GTIN, batch and dates | Printed or laser-marked; small |
| Data Matrix with a GS1 Digital Link URI | A web address built from GS1 identifiers | GS1-aware scanners and phones | Printed; usually larger than a GS1 DataMatrix with the same data |
| Plain Data Matrix | Any text the printer was given | Only the owner’s own systems know what it means | Same symbol, different content rules |
| Direct part mark (DPM) | Usually a serial or part number | Traceability of parts | Dot-peen or laser on metal or plastic |
How is a GS1 DataMatrix built?
The symbol is a grid of square modules. A solid L-shaped finder pattern, one module wide, runs down the left and along the bottom; the opposite two sides carry an alternating clock track that tells the reader the grid size. A quiet zone one module wide must stay clear on all four sides. Square symbols come in 24 sizes from 10 × 10 to 144 × 144 modules, rectangular ones in 6 sizes from 8 × 18 to 16 × 48; symbols of 32 × 32 and above are split into data regions by alignment patterns. Reed-Solomon error correction lets the reader rebuild damaged modules (GS1 General Specifications, 5.6.2–5.6.3).
Swipe sideways to see the whole drawing →
Worked example: how big is the code? GS1 counts FNC1, every pair of digits and every letter as one codeword (GS1 General Specifications, 5.6.3.2). Take FNC1, then (01)10614141123459, (17)271130 and (10)L2610A. That is 1 codeword for FNC1, 8 for the 16 digits of the GTIN field, 4 for the 8 digits of the expiry field, and 5 for “10”, “L”, “26”, “10” and “A”: about 18 data codewords. GS1’s Table 5-32 gives the 18 × 18 symbol exactly 18 data codewords, so this fits, and a batch one character longer moves it to 20 × 20. Printers’ encoders may optimise differently; the arithmetic is for planning the space on the artwork.
| Square symbol | Data codewords | Numeric capacity | Side at 0.495 mm modules (without quiet zone) |
|---|---|---|---|
| 16 × 16 | 12 | 24 digits | 7.9 mm |
| 18 × 18 | 18 | 36 digits | 8.9 mm |
| 20 × 20 | 22 | 44 digits | 9.9 mm |
| 22 × 22 | 30 | 60 digits | 10.9 mm |
| 26 × 26 | 44 | 88 digits | 12.9 mm |
How big must it be printed?
Because a camera has to resolve each module, GS1 requires 2D symbols to be printed at 1.5 times the X-dimension allowed for linear barcodes in the same scanning environment (GS1 General Specifications, 5.12.3). The ranges are:
| Use | X-dimension (module size) | Quiet Zone | Minimum quality |
|---|---|---|---|
| Retail consumer item, in addition to the linear barcode (table 1, addendum 2) | Minimum 0.396 mm, target 0.495 mm, maximum 0.990 mm | 1X on all four sides | 1.5/12/660 |
| Retail item also scanned in distribution (table 3, addendum) | Minimum 0.743 mm, target and maximum 0.990 mm | 1X | 1.5/20/660 |
| Cases scanned in general distribution (table 2) | Minimum and target 0.743 mm, maximum 1.50 mm | 1X | 1.5/20/660 |
| Items not scanned at retail or in distribution (table 4) | Minimum 0.375 mm, target 0.495 mm, maximum 0.990 mm | 1X | 1.5/08/660 |
On retail items scanned at the till, a 2D barcode is used in addition to the linear barcode, not instead of it, and GS1 asks for the whole 2D symbol including its quiet zone to sit within 50 mm of the centre of the linear barcode, so the scanner can tell both belong to the same item (GS1 General Specifications, 6.3.3.1).
Where is GS1 DataMatrix used?
GS1 lists GS1 DataMatrix and QR codes with a GS1 Digital Link URI as the two most widely recognised 2D barcodes; both can carry the GTIN together with data such as an expiry date or a serial number (GS1, 2D barcodes). GS1 South Africa describes GS1 DataMatrix as a compact 2D barcode that holds a lot of data in a small space, used for example on healthcare and grocery products (GS1 South Africa, barcode types). Regulated healthcare packaging is outside addaScan’s scope; food and consumer goods lines are not.
For a South African packaging line, the practical uses are: a date and batch in machine-readable form on the unit, for stock rotation and recalls; a serial number on high-value items; and the same data on cases where a GS1-128 would be too long for the panel.
How is GS1 DataMatrix read on the line?
A fixed code reader or a smart camera with code tools reads it. Linear imagers and laser scanners cannot (GS1 General Specifications, 5.12.2.3). The reader must resolve the smallest module, so the module size and the field of view set its resolution; as a rule of thumb, plan for several pixels across each module and test on real samples. The GS1 DataMatrix Guideline describes three complementary production controls: verification as part of quality control, reading every symbol on the line, and sample checks (GS1 DataMatrix Guideline). A line station is the second of these.
- Decode every pack; a no-read rejects.
- Check the symbology identifier is ]d2, so a plain Data Matrix with the same characters fails.
- Parse the AIs and compare GTIN, batch and date with the run from the PLC or MES.
- Watch the quality trend: many readers report a decode-margin value; a falling value means the coder needs attention.
| Fault | Usual cause | What the reader sees | Fix |
|---|---|---|---|
| Missing or merged dots | Inkjet nozzle blocked, speed too high for the print head | Low modulation or no-read | Print head maintenance; slower print or larger module |
| Distorted grid | Pack moving unevenly under the printer; encoder not tracking speed | Grid non-uniformity, no-read | Encoder-driven print; stable conveying |
| Quiet zone violated | Code printed against a seam, text or the edge of a panel | No-read at the till, often fine on the line | Artwork and print position |
| Low contrast | Laser mark on a light film, or dark code on dark print | Symbol contrast low | Print window, ink colour, laser settings |
| Valid code, wrong data | Wrong batch or date in the coder; no FNC1; plain Data Matrix instead of GS1 | Reads perfectly; only a content check catches it | Expected values from the recipe; check the symbology identifier |
Choosing a code reader explains the selection; OCR/OCV and code inspection covers stations that check the code and the printed text together.
Is a direct part mark the same thing?
Related, not the same. A Data Matrix dot-peened or laser-marked onto metal or plastic parts is read under angled or diffuse light and graded with its own method, ISO/IEC 29158. Printed codes are graded to ISO/IEC 15415 (ISO/IEC 15415:2024). DPM code reading covers parts.
Frequently asked questions
Can a normal barcode scanner read GS1 DataMatrix?
Only an imaging (2D) scanner or camera can; a laser scanner or linear imager that reads linear barcodes cannot. Fixed code readers and smart cameras on lines are imaging devices.
Is a GS1 DataMatrix printed on our carton the same as the one on a metal part?
The symbol rules are the same; the marking process, the lighting needed to read it and the grading method differ. Printed codes are graded to ISO/IEC 15415, direct part marks to ISO/IEC 29158.
How small can a GS1 DataMatrix be on a retail pack?
GS1 sets a minimum module size of 0.396 mm for 2D codes on retail items. The overall size then depends on the data: a GTIN, expiry date and short batch fit in about 18 × 18 modules.
Does a GS1 DataMatrix replace the EAN-13?
Not yet at the till. GS1 requires 2D barcodes on retail items to be in addition to the linear barcode during the transition, placed close to it.
Sources
- GS1 General Specifications, Release 26.0 (Jan 2026), GS1 South Africa copy: 5.6, 5.12.2.3, 5.12.3, 6.3.3.1 (standard, checked 2026-10-27)
- GS1 DataMatrix Guideline (GS1 guideline)
- GS1: 2D barcodes (standards body page, checked 2026-10-03)
- GS1 South Africa: barcode types (standards body page, checked 2026-10-27)
- ISO/IEC 15415:2024, bar code print quality test specification for two-dimensional symbols (ISO catalogue page)