Code 39, also known as 3 of 9 Code and USD-3, is an alpha-numeric variable length symbology widely used in non-retail environments. Code 39 is often used in Libraries, Video libraries, asset barcoding, serial number barcoding, forms management etc. Next to product barcodes (EAN or UPC) they are the most common barcodes in use today.

Code 39 may use a check digit, but often is used without a check digit. Code 39 is normally used to encode digits, upper case letters, and a few special characters. Representing lower case letters and most of the special characters is done using "full ASCII" mode. This requires twice as many bar code characters and consequently twice as much space on the paper. [↑]

To answer this question you must know a little about barcodes. So let's go through a few points.

1. Why are barcodes usually Black and White? Barcodes are read by an optical process and it is much easier for barcode readers to be able to accurately read the barcode if the "Bars" are non reflective (ideally black) and the "Spaces" are reflective (ideally white). Other colour combinations can work but their success depends on all sorts of criteria such as the colour, the reflectance, the resolution of the printer, the barcode reader.

2. Why is there a big space at the beginning and the end of the barcode? This area is called a "quiet zone" and the barcode reader needs it to determine where the barcode starts and stops. If this quiet zone is missing at either or both ends then the barcode may be able to be read but the chances are not good. [↑]



3. How are the bars and spaces determined? In the table below is a breakdown of bars and spaces used in a Code39 (sometimes called 3 of 9) barcode. It is not as complicated as it looks. Each Code39 Character consists of 9 segments, 5 bars and 4 spaces. Each character is separated by a small space. Bars and spaces have 2 sizes, wide and narrow. In the table below the 1 represents a wide and the 0 represents a narrow.



4. What are the Start Stop Characters? In the Code 39 Barcode this are the "*" character. These characters must be the first and last characters in any Code 39 Barcode. Without these in the correct spot the barcode will not scan. Looking at the Gripon Barcode below you can see them at the start and finish. Once you are used to looking for them you can spot them easily and this will help you determine any problems in your printing. You will notice they are identical.



1. Easy barcode to print.

2. Uses alpha and numeric characters.

3. All barcode readers are capable of reading it.

4. Can be easily printed with a barcode font. Download a demo font. [↑]

1. Takes up more room on the label than other symbologies.

2. Without a check digit, errors are possible with poor printing.

3. Can be difficult to read when printed densely. [↑]

1. Missing Start and Stop Characters. Without these characters the barcode cannot be scanned.

2. Barcode does not fit. This is possible with lots of data. Be careful that the barcode itself has it's quiet zones and is fully printed on the label or the form. Be careful when putting boxes around barcodes as they can interfere with the quiet zones.

3. Barcode doesn't scan. This could be anything but you should check that the barcode is not printed too densely. Remember a barcode reader is an optical device. If you cannot see it clearly yourself then chances are the barcode scanner cannot also. Do a visual check of the Start and Stop characters to make sure they are the same. If you are using a barcode font then sometimes other characters "sneek" into your barcode at the end of your barcode. You should be able to spot this with your visual start stop check. Make sure you test your barcode reader on a known good Code39 barcode just in case it is the reader. [↑]

1. Use it to attach serial numbers on your products.

2. Uses it to print your own in house product barcodes.

3. Use it on forms to aid tracking.

4. Use it on Assets to help tracking.

5. Any task using barcodes, your mind is the limit! [↑]

If you would like to purchase a barcode reader, barcode fonts, printing software etc just call 1300 762 603 or email sales and we will discuss your needs with you. [↑]

If you need further help, would like to be advised of future tutorials, or have a tutorial suggestion just email us.

This tutorial is copyright Pos Shop Pty Ltd. You are free to distribute this or publish this to others provided it is distributed without changes and complete. Whilst every care has been taken to ensure the accuracy of the information provided, no warranty whether implied or stated is given as to the information's accuracy or suitability. As we are not aware of your exact situation the content is used at your own risk entirely. [↑]

Ces Luscombe has worked in the Barcode and POS industry since 1995. Ces is the founder of The Barcode Approach (later to become Gripon Australia) and is also the founder of Grabba International Pty Ltd. Grabba International was formed as a result of a spinoff from Gripon Australia Pty Ltd after the successful worldwide launch of the Grabba PDA Data Capture attachments in San Jose, California in 2002. [↑]

Pos Shop Pty Ltd is a leading reseller of point of sale equipment, signage, ticketing and shop fitting accessories. Pos Shop was established in 2003 to service businesses and shopkeepers alike. The Pos Shop offers an unsurpassed range of goods to help businesses in all aspects. For more information contact us or telephone 1300 762 603. [↑]