Azalea Software, Inc.

What kind of barcode is this?

Sometimes you have a bar code and need to tell what kind it is. Identifying which bar code symbology you're looking at is easy if you apply a few simple rules of thumb. There are ways to tell which barcode symbology is in front of you.

Answering three simple questions can go a long way to determining which type of bar code you're dealing with:
  - What is the bar code on? Retail item, letter, form, etcetera
  - Is it on US mail? A part of the address block
  - What do the first and last set of bars look like? The start and stop bars

What is the barcode on?

If it's on an item destined to be scanned at a cash register, it's a UPC (US and Canada), JAN (Japan), or EAN (the rest of the world) symbol. All of them usually have two notches on the bottom with numbers (and only numbers) inside the notches. UPC-A symbols have five digits in the left and in the right notches, EAN and JAN symbols have six digits in each notch. If there is only one notch, it's a UPC version E barcode if it has six digits, and either a EAN-8 or a JAN-8 if there are seven digits.

If the barcode in question is on a book, it's probably an ISBN-13 bar code, called such because they're based on an ISBN number. ISBN-13 barcodes are sometimes referred to as Bookland barcodes, an older name for this type of barcode. ISBNs begin with "978" and have a 5-digit supplemental bar code on the right. Some books that are likely to be sold at places other than bookstores often use a UPC instead of, or in addition to, an ISBN. This includes children's books, some religious books and romance novels.

If it's on a shipping label or an ID badge it's likely a Code 128 or a Code 39 bar code. Sometimes other symbologies are used but typically in specialized vertical-market situations.

If it's on a corrugated box it may be an Interleaved 2 of 5 (ITF) symbol, especially if it has a 1/4" bar above and below it, or a 1/4" frame all the way around it.

Is it on US mail?

If it's on a US letter and has tall and short bars, it's a POSTNET (zip code) barcode.

POSTNET and the newer PLANET bar codes are used on US mail. POSTNET and PLANET barcodes encode the ZIP code and sometimes a portion of the address. They are distinct in that they employ alternating tall and short bars, instead of alternating wide and narrow bars. The first and last bars are always tall.

What do the first and last set of bars look like?

Most bar code scanners read a number of different barcode symbologies. They look for unique patterns of bars at the beginning and end of each symbol as a way to determine what type of bar code they're looking at. Similarly when creating a bar code, you must use the correct start and stop bars for the symbology at hand. Therefore if you can identify the start and stop bars, you can tell what kind of bar code you're looking at.

Code 39 is one of the oldest and most widespread bar codes in use today. It uses the asterisk as its start and stop bar. Look for the same pattern of bars on the left and the right sides. The pattern is narrow bar, wide space, narrow bar, narrow space, wide bar, narrow space, wide bar, narrow space, narrow bar.

Code 128 is commonly used for ID, inventory, tracking and especially as part of many shipping label specifications. There are three main dialects of Code 128: code set A, code set B, and code set C. All three code sets use the same stop bars on the right. Identify the stop bars correctly and you'll know it's Code 128.

Once you've narrowed it down to Code 128 based on the stop bars on the right, see if you can isolate the start bars on the left so you'll know which code set it is: A, B or C.