When these codes are printed, it's crucial that each element is legible for a smartphone or scanner. The texture of your material, the print process, the ink color, and the size of your code can all affect the clarity of the printed code, and in turn the scannability.
There are several best practices to ensure that your printed code is scannable, but keep in mind that the best way to ensure a printed code is scannable is to pull out your phone and test it.
The texture of your material is one factor that can affect scannability. The more textured and uneven your surface, the more likelihood that ink could spread, blurring the lines between elements. For better scannability, your code should be larger on more textured surfaces.
In general, paper surfaces are more textured than plastic. For example, the paper fibers of a box create a more textured printing surface than the melted polymers of a poly mailer.
Beware of printing on glossy surfaces. The shine creates a glare that can prevent easy scanning.
A rule of thumb for the size of a QR code is
Scanning Distance ÷ 10. So if your code is scanned from 10 inches away, it should be 1 inch across. This is a great starting point, but a more consistent print metric to consider is line weight.
While the size of the code matters, it's also important to consider the amount of white space around the code and between its modules. A module (aka X-dimension) is the smallest unit in a scannable code. In a QR code, a module is an individual square. In a barcode, a module the thinnest bar.
Error correction: QR codes can vary in complexity depending on the amount of redundancy (aka error correction) and the length of the url. Error correction repeats module groupings to increase the likelihood of scannability even if your code gets damaged.
With a QR code generator, you can choose a level of error correction: Low, Medium, Quartile, or High. The higher the error correction, the more modules will populate your QR code, so you'll likely have to size up to meet the minimum module width.
Each print process has different capabilities and ink traits which can affect the precision and clarity of an image.
If you're using a less precise print process (like flexographic printing), you should consider scaling up your code to increase the minimum module width (1.5 pt) to account for any ink bleed that could fill the gaps between the modules and affect scannability.
Colors to avoid
Some QR code scanners can't read light colored codes printed on dark backgrounds — this includes light ink on natural kraft. To be safe, we advise printing your code in a darker color on top of a light colored ink or material.
If you're printing a barcode, avoid using red to print the code itself because laser scanners read red as white.
Your code should be as high contrast as possible so that it's easily distinguished from the background. Your contrast ratio should be at least 4:1. You can use this tool to find the contrast ratio of your colors.
Tip: If your packaging design uses just one color of ink, adding a second color for your barcode or QR code adds the cost of a second print plate.
To avoid a second print plate and keep your code dark-on-light, consider removing a square of your ink color and printing your code inside of the empty square, using your one ink color.
If you want to err on the side of caution, bigger codes are better, and avoid printing in light colors.
If you have any doubts about the scannability of the final print, your best bet is to test it. If you have time to get a printed prototype before your full run is produced, that is ideal.
When you download a Lumi ID QR code, it's already saved in the SVG format.