Barcode Symbology Explained: 1D vs 2D Types

Symbology simply means "a system of symbols". In barcoding, each symbology has its own rules for which characters it can encode, how bar widths or module positions represent data, and how a scanner checks that a read is correct. That is why people also call it the barcode type.

Almost every symbology is built from the same parts:

The width of the narrowest bar is called the X-dimension. A smaller X-dimension gives a denser code, but it demands better print quality and a higher-resolution scanner.

1D (linear) barcodes store data only in the widths of bars and spaces, so capacity is small and they usually hold a reference number that points to a database.

A common misunderstanding: the 899 prefix on an EAN-13 shows that the company number was issued by GS1 Indonesia, not that the product was made in Indonesia.

2D barcodes store data both horizontally and vertically, so they hold far more and still scan when partly damaged thanks to error correction.

The QR Code was developed by Denso Wave in Japan in 1994 and now underpins QRIS, Bank Indonesia's standard for payment QR codes. Data Matrix can be laser-etched straight onto metal or plastic, a technique called direct part marking (DPM).

This is why symbology matters when you rent or buy scanners: not every scanner reads every barcode type.

One more trap: many scanners leave the factory with some symbologies switched off to prevent misreads. If a clearly printed barcode will not scan, check whether its symbology has been enabled using the configuration barcodes in the scanner's manual. For warehouse workflows that need an app running on the device, rather than just sending scans to a computer, consider a PDT.

You can recognise the common symbologies by eye:

• 13 digits under the bars, with the first digit printed outside the bars on the left: almost certainly EAN-13.
• 12 digits with small digits at both ends: UPC-A.
• 14 digits inside a heavy frame or between thick top and bottom bars (bearer bars): ITF-14.
• Text that starts and ends with an asterisk, such as A123: Code 39.
• A square with three square markers in three corners: QR Code.
• A small square with a solid L-shaped border on two sides: Data Matrix.
• A rectangle of tightly stacked rows that looks like a pile of tiny barcodes: PDF417.

The surest method is to scan with a reader app that displays the code type, or switch on the scanner mode that transmits a symbology identifier. That check is worth doing when you match supplier labels against your warehouse system before a stock-take.

If you are the one specifying the barcode, for IT asset labels or warehouse racking for example, use these rules of thumb:

• Code 128 for short alphanumeric asset numbers. It is compact, every 1D and 2D scanner reads it, and almost all inventory software supports it.
• QR Code when the label needs a URL or longer data, or must be scannable with a phone camera.
• Data Matrix for very small labels, such as on chargers and accessories.
• Follow GS1 standards (EAN-13, GS1-128) when other parties, such as retailers or couriers, will read the code.

Print quality matters as much as the choice of symbology. Asset labels that get handled often should be printed on a thermal transfer printer so they do not fade, as explained in the article thermal label printers for warehouses; the printers are in the Zebra ZD series catalogue. Matching units to records during an audit is covered in IT asset audits. Scanners for stock-takes or events are on the barcode scanner rental page, with rate ranges on barcode scanner rental prices.