What are QR codes and how you can use them


What are QR Codes?

A QR Code, an abbreviation for Quick Response Code, is a 2D bar code made up of varying combinations of small squares. QR Codes can contain information such as a message, telephone number or web address, and once scanned with a device such as a smart phone will present the information to the user. Originally the QR Code was developed for Toyota to be used in motor industry, but since then a wide range of other uses have been found.

How does a QR Code work?

The black squares that make up a QR Code are placed in a sequence to a specification that will allow scanners or devices like smart phones to read them. Some of the squares are reserved (for example you'll note there are three larger squares in top left, right and bottom left), which are used as positioning markers, and some of the squares around them may also indicate what type data is being stored. The rest of the squares contain the actual data, for example a web address, which after being scanned would allow you to visit the site.

How much data can you store in a QR Code?

It can be used to store up to 177 rows and columns of data - in practical terms that equates to 7089 numerical characters or 4296 alphanumerical characters (due to the different encoding). This compares with just 30 numerical characters in a traditional bar code.

What size does a QR Code need to be?

In general terms, the bigger the QR Code the easier it is for a scanner to read, commonly scanners can effectively scan codes as small as 2cm, but you can also blow up QR codes to any size. The minimum size of a QR Code is determined by the distance the scanner will be from the code, and the how much data you need to store (the more data you store, the smaller the squares become, the harder it will be for the scanner to read). Most QR Codes can be represented in a size small enough to put on a business card.

Take a look at these two different bar codes and the difference in appearance depending on the amount of data being stored:

Alphanumeric 34 Characters


Alphanumeric 619 Characters


What are QR Codes used for?

Usage of QR codes have become particularly wide-spread in marketing as they're an excellent way to cram a lot of information into a small space that can then be consumed by users on devices with scanners, which these days is available on just about every smart phone and tablet. Search on your app store for QR Code Scanner and you should find plenty of free options available. Once you've opened the app simply hold up your camera to the QR Code to read the data. Let's take a look at some specific QR Codes that can be generated.

Plain Text

The simplest type of data to store, a text-based message. You can scan these examples from the screen on your smart phone or tablet:


Website Urls

This is a very common use because it saves the user typing in the URL - simply scan and go to the site!


Telephone Numbers

QR Codes make it easy to give customers your number, these could be useful for a business card, or you can even generate a contact card with more data.


Contact Cards

To provide a bit more information, a MECARD let's you provide your name, address, telephone and email, great for business cards.



A more unusual use, you can draft an SMS. This might be useful for advertising for example, to text to make a donation to a cause.


GEO Location

Providing a GEO location will allow users to open your location on Google Maps, great for finding offices.


WIFI Access

No more reading the bottom of the router every time your have a visitor - save your wifi credentials into a QR Code, scan and connect!


Connect on Skype

Let people connect with you on skype by embedding your username:



Start a facetime session by embedding your number:



Create quick payments with PayPal pay now QR Codes:


How can I create a QR Code?

To generate QR Codes in code there are PHP and JQuery libraries you can use. Alternatively all the examples in this article can be created using our Qr Code Generator tool.

QR Code Generator Tool

David Bainbridge

Coveloping co-founder and regular contributor to the Coveloping blog. David is a contract web developer based in Bristol, UK also posting code snippets and tutorials on the Code Synthesis blog.

Coveloping Membership

Access to a range of developer tools, get your first month free

Start Your Free Trial

Don't miss out!

Sign up to our newsletter for the latest news from Coveloping

Leave a Reply


Code Copied!