Decoding Barcode Symbologies

Barcodes have its own language or system of encoding, which is referred to as barcode symbology. It’s the method by which characters to be encoded are changed into a barcode’s black and white lines. To be able to print a barcode, a barcode printer must be able to understand the symbology of a particular barcode. In the same way, a barcode scanner has to be able to read or decode a barcode’s language to change back the lines into recognizable characters such as numbers, alphabets and symbols.

†Components of a Barcode

A barcode symbology typically includes the following:

  • Series of black lines and white spaces that contain encoded characters or digits.
  • Start and stop characters to mark the beginning and end of the barcode
  • A quiet zone (blank space) that is required on either sides of a barcode for accurate scanning
  • Check digit or checksum character as the last digit to verify the barcode has been correctly entered

†Character Set

The most important component of a barcode is the encoded string of characters. Different barcode symbologies used by printers from manufacturers allow different sets of characters to be encoded. Some symbologies can be numeric only while others are alphanumeric. Knowing what characters are allowed by a certain symbology is important in choosing the most appropriate barcode type.

†1D and 2D Barcodes

1-Dimensional (Linear) Barcodes: These are the typical barcodes that come to mind when one thinks of a barcode. A 1D barcode has vertical bars where information is encoded in a horizontal position as it would be written out by hand.

2-Dimensional Barcodes: A 2D barcode stores data horizontally as well as vertically in a graphical image that appears either as small squares or hexagons inside a square. Its construction allows it to store more than 7,000 characters versus the 20- character limit of a 1D barcode. A barcode scanner must scan the entire barcode from all sides to decode its information.

Popular Types of Barcode Symbology

There are several different types of barcode symbologies. Each type came about as the standard used in a particular industry or groups of industries as a solution to a problem. Here are the most common barcode symbologies.


Initially developed to address the needs of retail grocery stores, the UPC code is used specifically for the retail industry. Itís the barcode you will find on consumer goods and food in stores in North America, UK and other countries. UPC barcodes have a fixed length with the UPC-A containing 12 digits and the shorter UPC-E containing 6 digits, both all numerical. The Universal Products Commission strictly controls the printing standards of this code.


Used in Europe, the EAN barcode is also for retail products such as groceries, clothing and other consumer items. The default format of this code which is used worldwide is EAN-13, which comprises of 13 numerical digits, but there’s also EAN-8 format with only 8 digits for printing on limited space.

Interleaved 2 of 5

Also known as ITF, these barcodes consist of 14 numeric digits and are typically used for inventory, packaging and shipping. This is a compact barcode with both the bars and spaces able to encode information. These are the barcodes you’ll find on ground shipping boxes and delivery boxes on grocery stores.

Code 39

This is the most common barcode used for non-retail industries. It was developed to solve the need of some industries to encode both numbers and alphabets into their barcodes. Code 39 is used for inventory, identification, forms, manufacturing, shipping and warehousing. Because it’s alphanumeric and can encode some mathematical symbols, its length can vary. It also uses an asterisk for its start and stop.

Code 128

This is the standard in one-dimensional barcodes and is the typical code used in distribution and shipping. Code 128 is quite dense, meaning it can encode more characters, and it also contains a check digit for accurate scanning. A subset of this code is GS1-128, which is widely used all over the world as a product ID code in packaging and shipping.

Which Barcode Symbology Should You Use?

Choosing the right type of barcode can be confusing but the information above should give you a good guide on what is the most appropriate for your use. Keep in mind that some barcodes are used specifically by some industries and that a certain type of data may require a particular format. For retail environments, use either UPC-A or EAN13 barcode, which is the worldwide retail barcode used today.

For in-house tracking of inventory, you can use the common code 39, which is one of the simplest symbology. However, while code 39 is alphanumeric, it only allows uppercase letters.† A more modern and popular is the dense Code 128 if you’re looking to encode much more data into your barcodes. This symbology has three variants that you can choose from depending on the specific character set that you need.