barcode faq

common questions about barcodes

Code 128 FAQ | Code 39 FAQ | Interleaved 2 of 5 FAQ | ISBN-13 FAQ | UPC FAQ

This Barcode FAQ is a great way to learn about barcodes and bar code terminology. Questions about how to use Azalea software are answered on our technical support page. Read more about software licensing here.

Help! How do I get started with barcodes?

1. First decide what barcode type (symbology) you need. Are there standards or guidelines you have to adhere to? They will specify which symbology to use. If you're working with a business/trade partner who requires a specific barcode, ask them to provide you with detailed information. They should have written or online specifications to share with you.

2. What will be the barcode be used for? If you need barcodes for retail products use a UPC, EAN or ISBN-13 barcode. For ZIP codes on U.S. mail use POSTNET. For labels or forms in shipping or inventory Code 128, Code 39, or Interleaved 2 of 5 (ITF) can be used.

3. Once you’ve determined the barcode type, outline your workflow. Things to think about:
    - Do you need to print your barcodes, or are you emailing them to a coworker or business partner?
    - Will you print the barcodes yourself, or will you use a professional printer?
    - Will your barcodes be printed onto documents?
    - How will you check the scannability of your barcodes: do you have an in-house barcode scanner or software for your smartphone or will your trade        partner scan and test the barcodes for you?

We want you to succeed when you print barcodes. The more you know, the better your results will be. Have a look around this site: check out the many How-To's, the different barcode FAQs, and our tech support page. Play with our free barcode demo font. If you still find yourself stumped, give us a shout - we’re here to help!   return to top

What are barcodes?
Barcodes (bar codes) are machine-readable symbols used to store bits of data. Barcodes are used for identification, tracking, inventory, and as part of retail point of sale (POS) systems. Barcodes are integral to machine-to-machine communication, transmitting bits of data often without human intervention. Barcodes are everywhere in the modern world, and now you’ll start noticing them all around you!  return to top

What are barcode specs and standards?
Various standards bodies regulate the use of barcodes. Some standards describe physical characteristics (shape, size, data structure, character set, etc.) while others describe how barcodes are used in context (shipping standards, labeling standards, electronic exchange standards, etc.) The important thing is that everyone who creates or scans a barcode agree beforehand. See the bottom of this page for a partial listing of barcode standards bodies.   return to top

What are the benefits of using barcodes?
Barcodes enable automated work processes without human intervention. Auto ID technology like barcodes is often called keyless data entry. Barcodes are fast and accurate, never dyslexic or hungover. The use of barcodes eliminates many errors and often saves time and money. Consistent results without error at minimal cost. What’s not to love?  return to top

What types of barcodes are there?
At first glance all barcodes look pretty much the same: bars and stripes. The patterns aren’t random by any means. The various types of barcodes are called symbologies and examples include UPC, Code 128, Code 39, Interleaved 2 of 5, and QR.

Not only do the different types of barcodes differ in their geometry (pattern) they encode different types of information. Some are fixed format, fixed length numbers-only symbols (for instance, UPC barcodes). Most barcode patterns are variations in bar and space width. The POSTNET barcodes used on mail differ in bar height instead.

The barcodes that look like picket fences or ladders on their side are called 1D (one dimensional) barcodes. Examples include UPC, Code 128, Code 39, Interleaved 2 of 5, and Codabar. Others are rectangular and look like crossword puzzles or checkerboards. They’re called 2D (two dimensional) barcodes. QR barcodes scanned with smartphones are a popular 2D barcode symbology.

The most common barcode symbologies are listed here on this page.  return to top

What’s a barcode scanner?
Barcode scanners (also called barcode readers or barcode wands) are optical or laser devices that scan and decode barcodes. They interpret the varying widths of bars and stripes or the matrix patterns of the barcode, then transmit the data into readable text format or initiate an action within a program or mechanism. Most scanners can read most barcode symbologies except cash registers, which typically only scan UPC barcodes (EAN or JAN in Europe or Japan). Barcode scanners auto-discriminate based on each symbology’s unique start and stop bar patterns at the beginning and end of a symbol.  return to top

What’s in a barcode?
Barcodes can contain all different kinds of information, depending on which barcode symbology you’re talking about. Many 1D barcodes like UPC or Code 128 are simple lookup numbers linked to a database that contains the real data. The UPC barcode on a box of cereal is tied to a database that knows its name and price, subtracts 1 from the store's inventory, etc. Other barcodes contain small chunks of text. An example is an ID badges with your first name, last name and employee number.

More complex codes like QR and other 2D barcodes can contain entire paragraphs of information, including phone numbers, mailing addresses, latitude/longitude information, or internet addresses. Many barcodes include a check digit to insure data integrity.   return to top

2 of 5 (non-interleaved)
While increasingly rare, 2 of 5 barcodes are still used in certain situations, such as on some airline tickets and in photo-finishing labs. 2 of 5 bar codes, used to encode numeric data, are amongst the oldest barcode symbologies.

2 of 5 (non-interleaved) is frequently confused with its cousin, Interleaved 2 of 5, a popular and very common barcode symbology. Double check your requirements before purchasing 2 of 5 (non-interleaved) barcode software. There’s a good chance that you actually need Interleaved 2 of 5.  return to top

2D barcode
2D, or two-dimensional, barcodes are more complex than standard 1D barcodes. They contain larger chunks of information and are rectangular or square with a black crossword-like grid or 'honeycomb' pattern. 2D barcode symbologies include DataMatrix, QR code, PDF417, and a few others. A special 2D barcode scanner is often required to read 2D codes except QR barcodes which can be scanned with smartphones (and the right scanning app). Many standard barcode scanners are designed to only read 1D barcode symbologies like Code 128 and UPC.  return to top

Bookland is an older barcode format used on books. It has been replaced by ISBN-13 barcodes (International Standard Book Number). The two terms are sometimes used interchangeably but ISBN-13 is correct.  return to top

Check digit/check sum
A check digit - or check sum - is a character appended to the data encoded in a barcode. Its purpose is to confirm the integrity of the scanned data. Check digits are based on algorithms and can be calculated in a number of different ways, depending on the type of barcode. The are mandatory in some symbologies like Code 128 and UPC, optional in some like Code 39, and superfluous in Interleaved 2 of 5. Specific implementations and specifications may dictate check digits separate and apart from the basic symbology.  return to top

Codabar is a numeric symbology used by FedEx, libraries, and blood banks.  return to top

Code 128
Code 128 is a very popular barcode symbology used in a number of different situations. It’s dense and compact, squeezing more data into a space compared to Code 39. It’s variable length, alphanumeric and supports the lower 128 ASCII characters. Code 128 includes a mandatory mod 103 check digit.

Widely used in the shipping industry, Code 128 has three variations: code set A, code set B, and code set C (sometimes called 'subsets').
    code set A - uppercase letters, 0-9, and lots of control codes
    code set B - uppercase & lowercase letters, 0-9, etc.; most closely mimics the lower 128 ASCII characters
    code set C - numeric only with built in 2:1 compression resulting in very narrow symbols left-to-right

GS1-128 barcodes are a specific format of Code 128 that includes a FNC1 character at the beginning.  return to top

Code 39 (Code 3 of 9)
Code 39 (sometimes called '3 of 9') is an older and still popular symbology used for ID, inventory, and tracking purposes. It has a variable length, supports alphanumeric (numbers and letters) strings, and can be printed at a variety of sizes and aspect ratios. This is the bar code used anywhere a simple, plain vanilla bar code is needed. The standard character set is A-Z uppercase, 0-9, and handful of punctuation. The full ASCII version supports the lower 128 ASCII characters but the symbols are twice as wide. There exists a very rarely-used optional check digit.  return to top

Code 93
Code 93 is a rarely used, compact barcode symbology used on electronic components. Due to the similarity of their names, Code 93 and Code 39 are easily mistaken for each other in conversation when purchasing barcodes or barcode software. If you believe you need a Code 93 barcode be sure to double check your spec.   return to top

Data Matrix
Data Matrix is a 2D (two-dimensional) symbology that can contain a large amount of data including all letters, numbers and punctuation marks. It’s the basis for the UID (Universal Identification) symbols mandated by the Department of Defense.  return to top

EAN stands for European Article Number. EAN barcodes are used on retail items outside the U.S. and Japan and in a variety of other ways, including product identification in the global retail channel.  return to top

GS1-128 (EAN-128)
A GS1-128 barcode is a special type of Code 128 barcode that encodes GS1 System element strings.   return to top

Human-readables are the numbers or characters above or below a barcode, printed specifically to be read by people.   return to top

Interleaved 2 of 5 (ITF)
Interleaved 2 of 5 is a numeric-only symbology that is relatively compact because information is encoded in both the bars and the spaces. Interleaved 2 of 5 bar codes are used on corrugated boxes, in the shipping industry, and in laboratories. Do not confuse it with 2 of 5 (non-interleaved), an older bar code that isn’t used much today.  return to top

ISBNs (International Standard Book Number) are the retail barcodes used on books and book-related products. They are EAN-13 barcodes with a 5-digit supplemental. The former is the book’s ISBN and the latter the cover price.  return to top

ISSN stands for International Standard Serial Number. ISSNs are used on print or electronic periodicals (newspapers and magazines).  return to top

MaxiCode is a 2D symbology that resembles a honeycomb used by United Parcel Service for fast package sortation.  return to top

MSI-Plessey is a numeric symbology used in libraries.  return to top

2D (two dimensional) symbologies are extremely dense bar codes that look like a crossword puzzle or a honeycomb-like matrix. PDF 417 is found on the backs of many states’ drivers licenses. PDF417 codes can contain up to about 1100 bytes of information, and must be scanned using a 2D barcode reader.  return to top

POSTNET bar codes are used to encode ZIP codes on U.S. mail. Unlike other bar codes, POSTNET symbols consist of bars that vary in height, not width. A check digit is appended to the bar code, which can be used for 5-digit ZIP codes, 9-digit ZIP+4 codes or 11-digit Delivery Point Barcodes.  return to top

QR code
QR (Quick Response) barcodes are 2D (two-dimensional) barcodes invented by Denso Wave. QR barcodes are usually scanned with smarthones using a scanning app.

Compared to 1D barcodes, QR bar codes can contain large amounts of information including things like contact information, latitude/longitude data, web addresses or large chunks of text. QRs can be scanned by cell phones as well as dedicated 2D barcode scanners.   return to top

Supplemental barcode
Supplemental barcodes are the additional barcode to the right of a UPC, EAN or ISBN-13 barcode. Supplementals are eith 2 or 5 digits.  return to top

UPC (Universal Product Code) bar codes are used in the U.S. and Canada on retail items. UPC barcodes are the ones that are scanned at cash registers.  return to top

Specifications and Standards
    •   ANSI - American National Standards Institute
    •   Association for Automatic Identification and Mobility
    •   Bookland
    •   EAN
    •   ISBN
    •   ISO - International Organization for Standardization
    •   ISSN
    •   UPC
    •   JAN