|Summary: Is there a maximum QR code size? Answer: Technically, no. Practically, yes.|
You can create a QR code as large as you like an still satisfy the technical requirements that makes it a QR-code. However, if your goal is to create a usable QR code, it must fit within the viewfinder on a prospect’s smartphone. You should always consider where you expect prospects to be standing when they scan a QR-code.
A company called Blue Marble calls it “marketing from space.” Traditional billboards can cost between $10,000 to $30,000 per month. Blue Marble claims that a rooftop QR code costs 75 to 98 percent less than traditional billboards. They will create a QR code on your rooftop for $8,500 and guarantee that it will appear on a Google maps image for at least 12 months.
If you want to make a large QR-code yourself, you can easily be paint a QR-code of any size using any contrasting paint, or use contrasting vinyl flooring tiles for a moderately sized QR code.
Presumably, the companies who are placing QR-codes on building rooftops are expecting their QR-code to be scanned by either air travelers or extra-terrestrial beings using telescopes.