How do QR Codes work?

Have you ever wondered how your cell phone can scan that bunch of squares and extract some kind of information from that? In this article the website oQR Code who specializes in producing free QR codes explains to you.

2D and 1D Codes

There are different dimensions of codes, which we call 1D and 2D. Do you know the difference?
1D codes are those that have only one reading dimension, which is vertical reading, also known as barcode.
Barcodes are read from left to right, and each bar represents some type of character through the intervals between positive (black) and negative (white, or otherwise not black) streaks.

QR codes are 2D codes. This means that they can be read both vertically and horizontally, so it is called two dimensions. This makes it possible for QR Codes to store much more information than bar codes. For a comparative notion, a single QR Code can store 354 bar codes!


Although QR Codes look like a bunch of black pixels scrambled into a square, they do have some patterns for all the codes created. Some patterns are more visible to the naked eye than others, let’s see two here.

The first thing you may have noticed (and if you haven’t noticed it, you will start to notice it now), is that all QR Codes have three squares at their ends, except in the lower right corner. These squares serve to indicate which is the “correct side” for reading the QR Code. This means that even if you turn a QR Code upside down, through these three reference squares it is possible to know which is the right side to start reading.

The second, however not so noticeable, is the alignment squares. According to the number of information that needs to be saved in a QR Code, it starts to become very polluted and difficult to read, and this is where the alignment squares come in to delimit a region and prevent QR Code readers from passing two times for the same place.

First pattern
Second pattern

The saved information

Every time someone creates a QR Code is a code generated with several other unique squares that never existed before?
Well, not really.
Each of these black pixels are binary characters, that is, they represent the value 0 (zero) or the value 1 (one), and nothing more. When these heaps of zeros and ones are combined, the information that we can understand is formed.
This means that if you create a QR Code that links to the website, exactly with these letters, the number of box numbers will always be the same and will always be in the same places, no matter where or when you create them.
The image below exemplifies a simpler way to see how this works.


We have prepared a list of curiosities and legal information about QR Codes:

  • QR Codes can store up to 7,089 characters.
  • Barcodes can store only 20 characters.
  • QR Codes can lose up to 30% of their information and are still able to be read.
  • Because of the item above, it is possible to insert images and customize them to your liking!
  • You can change all colors of your QR Code, the important thing is to have at least one fixed color to read the information.
  • Currently, the country that most uses QR Codes is China.
  • With a little skill it is possible to write/draw a QR Code in pencil on a paper and read it with your cell phone.
  • QR Codes can be read in any position, even from the side or upside down.

5 things QR codes do and you don’t know

After all the information provided in this article and also the curiosities listed above, there are still many other things that QR Codes can do and you didn’t know!
Visit our post: 5 things QR codes do and you don’t know.

How to create a QR Code?

This article is available on the website blog, which is a website specialized in creating QR Codes for free and simple.
To create your QR Code simply access the home page, choose the type of QR Code you want to create and also the address of that QR Code, and voila! Try it.

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