We published an article on how to create QR codes. QR codes are seen everywhere these days and you can use them to direct visitors to your website by printing them on your business card or your brochure.

You can also print cards with the QR code of your art work to post beside the work in a show. Visitors can then go directly to the image on your website if they want more detail about your work making it easy to draw them in to your site.

We recently had a query as to the appropriate size to make those QR codes. After some research with Google, we found a number of articles on the topic. One in particular did a study of the whole subject.

It turns out that the size is dependent upon how close the scanner (typically a smart phone) is to the object being scanned. If you are printing an add on the side of a building to be scanned, it needs to be considerably larger than if you are printing it on a business card or a brochure.

For a 1.25" image, the phone must be between 10" and 18" away depending on the phone. For a 1.75" image, the phone must be between 17" and 30" away.

The results of their study were summarized as:

• According to their results, the smallest practical size for a printed QR code is between 1.25" and 1.75″.
• The density of the QR code mattered less than they anticipated.
• Low lighting did not significantly reduce the maximum range.
• The Android phones had more trouble focusing in low light situations but had much better range than the iPhones.

A table in their article showed colour indications of the reliability of scanning � green meaning very reliable, red meaning failure. You can see the whole study at minimum-practical-size-of-a-qr-code.