Sizes listed always refer to an exact square shape because otherwise, your QR code will not function properly.
Effectively zero distance. These QR codes are expected to be interacted with from a small distance; it can be as small as the camera focus on your device can go.
Examples of QR codes at intimate distances:
Minimum size for QR codes at intimate distances
Recommend size for QR codes at intimate distances
This is the distance individuals maintain between each other. The length of the arm plays a major role in defining this distance and it ranges between .5 to 1 meter (1.5-3 feet). QR codes that fit into the personal distance are QR codes that are in your arm distance after extending your arm towards them.
Examples of QR codes at personal distances:
Minimum size for QR codes at personal distances
This is the distance that people feel comfortable with, in a social situation. It measures between 1-3 meters (3-10 feet). QR codes that are expected to be interacted within a social distance are QR codes positioned in places where many people are gathered.
Examples of QR codes at social distances:
Minimum size for QR codes at social distances
This is the distance considered to be well outside any social involvement. It measures more than 3 meters (10 feet and above). QR codes are expected to be interacted in a public zone.
Examples of QR codes at public distances:
Minimum size for QR codes at public distances
Because those scanning may not be directly next to the code, you’ll need to increase the QR code size depending on how far away they will be. For example, if a code on a billboard will be scanned at a distance of 10 meters, the code should be at least 1 meter wide.
Please see, https://delivr.com/faq/1289/qr-code-printing-guidelines-best-practices