Linear Barcodes—A Crash Course

Linear Barcodes—A Crash Course

Research & Diagnostics, Labware Marking, Barcode Basics | 11 November 2020

Posted by Lisa Sarvie

Linear Barcodes—A Crash Course

Barcoding is an accurate and efficient method for automated data collection. With proper barcoding also comes the benefits of rapid, accurate, and efficient information gathering, and easy transmission to a computer or centralized database. Implementation of a reliable, easy-to-use identification technology can drastically change a business for the better.

In order to ensure your barcode strategy is as efficient and accurate as possible you need to select the right identification technology for your application.

In this post, we cover the basics of linear barcodes to give you the necessary knowledge to make an educated decision on whether or not linear barcodes are the right fit for your processes.

What is a Linear Barcode?

A linear barcode is a common type of barcode comprised of a single row of bars and spaces. It’s probably what first comes to your mind when you think of a barcode. Linear barcodes are incredibly versatile, which is why you see them so often in your day-to-day life.

Data is stored within the lines—and sometimes the spaces—usually related to the tracking and identification of the barcoded item.

The bars are always black and the spaces are always lighter—typically white to ensure optimal contrast. Those bars and spaces are used to represent letters and/or numerals. The specific arrangement of the bars and spaces on a barcode follow strict rules to ensure no inefficiencies occur.

Scanners use light or a camera image to pick up the contrast between the bars, spaces and individual barcode components. The scanning device will transmit the barcode information to a computer where it can be decoded and displayed in a human readable format.

What are the Components of a Barcode?

Barcodes are a simple and convenient way to store information for quick and easy tracking and identification—linear barcodes being one of the most widely adopted barcode types—but what makes a barcode, a barcode?

Three components are necessary to build a functional linear barcode: the quiet zone, start and stop characters, and an interpretation line. Additionally, inter-character gaps are required in certain types of linear barcodes.

  1. The quiet zone: The quiet zone is the blank area adjacent QuietZoneGraphic
    to the beginning and end of the actual barcode symbol.
    Having this space allows the scanner to properly recognize
    and read the code. 

    Start&StopCodeGraphic2. Start and stop characters: Start and stop characters are found at the beginning and end of the barcode symbol. These characters tell the scanner which direction information is being received—horizontally or vertically.


3. Inter-character gaps: Inter-character gaps are not a required component to all barcodes, but in many cases it is necessary each individual character be separated from those adjacent for proper decoding.

  1. Interpretation line: The interpretation line is the line of text above or beneath a barcode where human readable information appears. The information contained in this line may or may not be the same as the data encoded in the barcode itself as this depends on the user’s needs and the application.
    Learn what these terms mean and more in our barcode glossary

Symbology: The Specific Barcode “Language”

A number of different symbologies exist within the linear category—for example:

  • Code 25, also called 2 of 5
  • Code 128
  • Code 93
  • Codabar
  • Code 39
  • Code 11

To name just a few.

Linear barcode symbologies contain a single row of bars and spaces that encode various types of data. For proper scanning and data collection capabilities, it may either use width or height modulation.

Each symbology is designed to complete a specific task, meaning different symbologies are best suited to different applications.

Some linear barcode symbologies contain only numerical data, while others contain both letters and numbers.

Another differentiation in symbology is whether the code is continuous or discrete. Continuous codes contain data in both the bars and spaces. In a discrete code the characters stand by themselves, requiring extra space between each adjacent character making them less space efficient than continuous codes.

In addition to linear barcode symbologies there are also various 2D barcode symbologies which are capable of holding more data in a smaller area than a standard linear code—check out this blog post to learn more about the differences between linear and 2D barcodes.

Linear Barcode Applications

Linear barcodes are extremely versatile and have been the standard in most industries for decades. Due to their popularity, just about any barcode scanner is capable of reading linear barcodes—this makes them a great choice for any application, especially if there are multiple scan points throughout your processes.

In lab settings it’s very common for tubes and vials to include both linear and 2D barcodes for downstream automation purposes. Including a secondary ID technology, such as 2D barcodes or RFID in a linear barcode strategy can be especially useful in situations where a back-up identification strategy, additional information or automation are a crucial part of your process.

Linear Barcode Integrity

Ensuring barcode integrity is extremely important in nearly every application, which is why we suggest you implement a sequence management system. While it is possible to do this in house, the most reliable way to ensure data integrity is by working with your supplier.

Not only will leaving sequence management to your supplier save you a lot of time and resources, but your supplier is likely to have a stringent process, committed team and specialized equipment solely dedicated to sequence management.

The one downside to relying on your supplier for sequence management services is that you must have the ability to order labels pre-printed (or pre-applied to labware where it applies.)


How to Achieve a Linear Barcode Strategy

There are numerous ways to achieve a linear barcode strategy—they mainly differ in printing & application strategy, and the marking technology used.

Printing & Application Strategy

There are three main print strategies when it comes to printing linear barcodes:

  • Printing and applying in house
  • Applying pre-printed labels in house
  • Receiving items with barcodes pre-applied (in specific applications)

Printing and applying labels in house is a very common strategy and is necessary for applications where information needs to be added on the fly. Print and apply automation can be utilized to reduce labor and increase accuracy.

Labels can also be ordered pre-printed if you are able to give your supplier necessary data ahead of time (sometimes with relatively short notice.) This eliminates the printing process from your facility and you can further optimize your system by implementing label automation.

In applications where consumables can be purchased with labels pre-applied—such as containers for laboratory use—as long as you have barcode information available ahead of time, or can opt for generic information pre-barcoded labware is a viable option.


Marking Technology

There are various marking technologies that can be used to implement a linear barcode strategy including:

Pressure sensitive labels are commonplace and suitable for a wide variety of applications. If you’re applying labels in house pressure sensitive is certainly the way to go, but if you’re purchasing consumables with markings pre-applied you will have access to additional technologies.

Special engineering can allow pressure sensitive labels to withstand a broad range of extreme conditions—chemical exposures, extreme heat and extreme cold.

Direct mark is one of the various options your pre-marked labware suppliers may be able to provide. This can mean laser marking, specialized ink application or a combination of both. Direct mark is a great way to include high resolution color imagery alongside barcodes and is comparatively more durable than pressure sensitive labeling.

Ceramic labels are fired directly onto glass containers making them extremely durable and capable of maintaining a stable tare weight. These labels are especially useful in compound storage situations where containers may be stored for decades, exposed to harsh conditions and/or need to maintain a consistent weight.


As you can see, there are several ways to go about implementing a linear labeling strategy. Ensuring you have the right printing and application strategy, as well as a suitable marking technology is crucial to ensuring the success of your strategy.


Linear barcodes are complex structures, but are famous for making identification processes easier and more efficient. If you’re considering implementing a barcode strategy to your business or process, we’d love to chat with you!

How can I improve accuracy & efficiency in my labware labeling strategy?

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Lisa Sarvie

Lisa Sarvie is the Director of Customer Excellence here at Computype. From St Paul, MN, she works very closely with customers to ensure a positive experience. Lisa’s team works to ensure the customer experience with Computype is consistently satisfactory. Additionally, her team manages customer accounts to ensure all needs and specifications are consistently met.