Printing QR Codes
People ask us every day about printing for QR Codes and what size is advisable. We are going to explain it in very simple terms because mistakes are made sometimes and we hope this article will help you overcome this.
To print a QR code you must have the QR Code in the correct format. Usually for print Vector images are advised as they can be scaled to any size. Use a generator that provides images in vector format; Azonmobile's can produce PDF, SVG and EPS Vector formats.
Printing small Raster Codes
In case you would like to use our more advanced customization features like foreground image or different styles the output will be a Raster. The first question is
"How big should the image be to enable it to be printed"?
Here is how to find out the minimum size the QR Code image in pixels has to be. Lets assume that you will print at 300dpi (dots per inch) quality and the size of the QR Code when printed needs to be 1.5 inches in size:
1.5 x 300 = 450 pixels
In case you prefer the metric system and you need a QR Code to be 4cm in size for example (1cm is 0.394 inches):
4 x 0.394 x 300 dpi = 473pixels
If the print quality is 600dpi then you will need 900px for 1.5 inch code and so on...
Having the necesary size in pixels of the QR Code you can play with the “block size” option of the generator to obtain the optimal result – an image that is large enough.
As the ad space is limited the next question usually is
"How small physically can a QR Code be in size"
The minimum size that can be scanned is affected by a few things - the distance, the QR Code colors, the phone camera. Assuming the QR Code is printed on a magazine or newspaper (something that the user is holding in ones hand) we can set the scanning distance at 10cm. In order to obtain best results in terms of readability we will assume that the code is plain black and white.
For a modern device with a camera of at least 4MP the minimum size of one square block of the code for the given distance of 10cm is 0.4mm. So for a code with 21 blocks in a row (the smallest QR Code possible) this would require it to be 8.4mm (0.331 inch) at least. This is the absolute minimum - to improve the readability (i.e allow scanning from a further distance) or if using a colored code you should go higher. If you would like to double the distance to 20cm you must double the block size to 0.8mm.In general you should never go for the smallest possible block as the printing technologies may blurr it a little!
The more information you input the resulting QR Code will contain more blocks (rarely they are just 21 blocks). For a QR Code with 40 blocks in a row in order to be scanned from 20cm it must be at least 32mm. Usually the biggest QR Codes are vCards - if all available fields are filled with data you will get a code that is so complex, and some readers can't scan it even in ideal conditions (right size & plain colors)! Because of this especially for vCards we recommend to fill the minimum possible information.
Also remember that the error correction also impacts the size of the QR Code by affecting its complexity - if you want to have a smaller code reduce the error correction. If the QR Code will be customized you should leave the error correction higher.
Printing big Codes
In case the QR Code has to be printed in a very large size (for example billboard) you should go for a Vector format. The Vector format is not measured in pixels - instead it can be scaled to any size. Still if you want to use the extra visual options provided by our generator for the raster images you can still use raster forma,t but you will have to generate a huge image using much higher values for block size - the calculations provided above are valid.
In large scale print the size of the code matters because of the distance from which it will be scanned. Above we were discussing the usual case of small print and the distances. The same rules are valid here too - for a QR Code to be scanned from 3 meters / 118 inches away (assuming right angle) the side of the code should be minimum 12 cm / 4.73 inches. We recommend you to print the codes a little bigger (by a factor of 1.2) just to ensure readability.
Few readers are able to scan a code from a further distance for the same code size than the rest, but this is not accounted for in this article neither you should rely on it!
- The QR Code block size must not be under 0.8mm for a normal user experience when used on a magazine or newspaper. In general do not print any QR Codes under 0.5inch as most probably they won't be readable no matter how few blocks they contain.
- Customized QR Codes usually should not be smaller than 1 inch when printed. Go for a larger code in case you have your logo embedded so it is visible.
- Complex QR Codes that contain a lot of data and have high error correction level may be hard or even impossible to read on some devices. Consider this when you are creating a vCard QR Code for your business card - do not fill too much data.
- Be aware that the colors that are output from the printer may be a lot different from what you see on the screen - this may concern the overall visual effect of a Customized QR Code or impact the readability of a colorful code.
- Before you make the bulk print order to your printhouse run a few samples and ensure that the QR Code is readable on the type of material/paper you print on. Test with as many phones as you can and preferably not all top-of-the line models. Only when satisfied with the result proceed with the printing. Always do samples and check the readability on paper specially for customized QR Codes.