The size of QR codes can vary considerably based on two factors: 1) how much information is encoded and 2) what the final application of the code is. We’ve seen made QR Codes that encode only a 5-digit product number printed at less than 1/3-inch squared. On the other extreme, we’ve seen QR Codes for use on highway billboards that were printed at about 4-foot squared.
Our clients’ QR Codes, on average, come out to around 1 inch by 1 inch in size.
Please keep in mind that the amount of content (the length of a URL, for example) affects the size of your QR Code graphic. The longer the URL, the bigger the QR code image will be. Therefore, you may consider using a URL shortener such as Bitly or TinyURL to shorten your website addresses and hence reduce the size of your smartphone barcodes (QR Code).