A Closer Look at Code 39



As promised in my Question of the Week, I’m going to take a closer look at Code 39 today.  Once again, Code 39 is also known as barcode 39, code 3 of 9, 3 of 9 barcode and more.  Code 39 was created in 1975 by Intermec and is still widely used in industrial applications and for internal applications.

Code 39 is capable of encoding uppercase letters A-Z, digits 0-9 and special characters such as SPACE, – (minus), . (period), $ (dollar sign), % (percent), / (slash), + (plus).  An Extended Code 39 can also encode additional characters not normally supported by the code, such as lower case letters.  This low density symbol requires more space to encode data than the similar Code 128.  Also unlike Code 128, Code 39 doesn’t require a check digit because it was designed with character self-checking.  Yet Code 39 does have a checksum character for standards that may require it, such as LOGMARS (Logistics Applications of Automated Marking and Reading Symbols).  When required, the checksum is calculated using a Modulo 43 calculation and the code is referred to as Code 39 mod 43.

Each Code 39 character is made up of 9 elements, 3 wide and 6 narrow.  Therefore, a single character consists of 5 black bars and 4 white spaces.  Each symbol includes:

1. Quiet zone the width of at least 10 narrow bars

2. Start character

3. Encoded data

4. Stop character

5. Quiet zone the width of at least 10 narrow bars

Code 39 can be read by nearly every barcode scanner on the market today and is quite popular because of its simplicity and reliable reading results.  If you would like more information about barcode software that supports Code 39 or have any additional questions, please feel free to contact me at ehodges@barcode.com.