Code 39

1D Symbologies

Symbology Code 39

Code 39 was the first barcode to use both numbers and letters, making it more versatile. It is one of the most extensively used barcodes. However, it is a lower density and less compact barcode compared to other barcodes such as Code 93 or Code 128.

The Code 39 barcode is one dimensional, named for its pattern of bars and spaces. It can encode up to 43 characters, including numeric digits (0 to 9), uppercase letters (A to Z) and several special characters (– . $ / + % and space).

Code 39 is also known as Code 3 of 9, 3 of 9 barcode, Alpha39, Type 39, Code 3/9, USD-3 and USS Code 39.

Characteristics of a Code 39 barcode

  • Is a discrete symbology and supports variable length data content, with no theoretical limit on code length.
  • Supports narrow to wide bar ratios from 1:2 up to 1:3; 1:2.5 is recommended.
  • Encodes numbers, capital letters and symbols.
  • No checksum is verified by default, but an optional mod43 checksum can be enforced.
  • Can be scanned as valid 32 codes and vice versa.
  • Standardized use through the ISO/IEC 16388 international standard.


Most barcode scanners can read Code 39 barcodes by default, including laser barcode scanners, linear imagers and smart devices equipped with a camera and barcode scanning app.

Scandit’s barcode scanning software supports all major barcode types, including Code 39 barcodes.

Regarding Code 39 barcode scanners specifically, the Scandit Barcode Scanner SDK:

  • Supports color inversion.
  • Has an optional mod43 checksum.
  • Enables (on demand) encoding of all ASCII characters, including control characters.
  • Enables scanning codes with quiet zones (white area before and after the code) that are significantly smaller than the symbology specification allows.

Application areas

Code 39 barcodes are used to label goods across many industries. It is currently the most widely used alphanumeric barcode and has been accepted as a standard code by many organizations, including:

  • LOGMARS (Logistics Applications of Automated Marking and Reading Symbols) is a standard the US Department of Defence uses to define where the barcode must be placed on a military shipment and what information must be encoded into the barcode to fit military specifications.
  • HIBCC (Health Industry Business Communications Council) is a labeling standard for patient safety and unique device identification.
  • AIAG (Automotive Industry Action Group) is the standard for labeling in the automotive industry.

Code 39 Scanner

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Code 39 FAQs

Where are Code 39 barcodes used?

Code 39 is used widely to label goods across many sectors including automotive, defense, electronics and healthcare. However, their low density and required size makes them ill-suited for very small goods and assets.

When was the Code 39 barcode invented?

Code 39 was developed in 1975 as the first alphanumeric barcode by Intermec Technologies.

What is Code 39 on a barcode?

There are many different types of barcode. Code 39 is a specific type of barcode. It was originally named because of its ability to encode a total of 39 characters. However, the latest version can encode up to 43 characters, consisting of uppercase letters, numeric digits and a number of special characters.

How many digits are in a Code 39 barcode?

A complete Code 39 barcode consists of up to 43 characters, including a start character (*), an optional check character (P) and a stop character (*).

How long can a Code 39 barcode be?

Code 39 barcodes are variable in length and capable of storing alphanumeric data of up to 43 characters. They support narrow to wide bar ratios from 1:2 up to 1:3; 1:2.5 is recommended.

What is the difference between Code 39 and 128?

Both Code 39 and Code 128 are popular choices for encoding alphanumeric characters in a barcode symbology. The differences are:

  • A Code 39 barcode can encode up to 43 characters, whereas the more powerful Code 128 can encode a full 128 ASCII character set.
  • Code 128 has a higher density than Code 39, making it generally easier to print clearly and decode.
  • Unlike Code 128, Code 39 does not require a check digit, making integrating it into an existing printing system easier.
  • Code 39 doesn’t support error correction, whereas Code 128 does.

What is the difference between UPC and Code 39?

UPC and Code 39 are both one-dimensional barcodes. However, a UPC can only encode single digits (0 to 9), whereas Code 39 barcodes can encode uppercase letters (A to Z) and several special characters (– . $ / + % and space), as well as numeric digits (0 to 9). Code 39 evolved from the UPC barcode.

How do you create a Code 39 barcode?

You can create a Code 39 barcode using Scandit’s free barcode generator tool.