Quick Response codes, or QR codes, are two-dimensional barcodes that contain encoded information that can be read and decoded by barcode scanners that utilize the cameras on smartphones. The design of the QR code is vital in order for the creator to get the intended message across to the viewer. Minimum QR size requirements exist for the types of information most often encoded, such as a webpage address or contact information. The codes may be enlarged from the minimum depending on how close to the user they’ll be displayed, as there needs to be a close enough distance for the camera to read the code.
The square shape of QR code matrices is designed for readability for the barcode scanner. Three sections positioned in the corners of the square provide a way for the scanner to orient itself and recognize how the code is presented. It is then able to run the data in the center through a decoding program, which includes a certain degree of error correction, before presenting the intended message to the user.
Minimum QR code size depends on the storage size of the data contained. Business cards displaying a code containing twenty-six characters of personal information can be as small as 0.6 by 0.6 inches (15 by 15 millimeters). A web address requires a minimum matrix of 1.25 by 1.25 inches (32 by 32 millimeters). Codes on a restaurant menu that contain a full wine list may require a matrix that’s 2.4 inches (60 millimeters) square and contains up to 739 characters.
The suggested minimum QR code size is based upon a camera range of 6 inches (152.4 millimeters). Doubling the distance for the camera also doubles the required QR code size, and tripling the distance triples the size. A code on a side of a building that’s meant to be used from the road will likely be the size of a billboard.
Creators of codes should keep QR code size practical to the medium and to the likely distance of the user. Business cards, for example, can have minimum-sized codes because users will most often be holding the card when it’s used. A code on a movie poster encased in glass and hung along an escalator will need to be larger to account for users who move close and away from it. Billboard-sized QR codes should only be used when absolutely necessary, as they’re likely to cause distraction for drivers and are impractical to shoot from too close to the building.