@quiet there's also a bunch of different QR code "versions" which are different sizes and also have different data density. there's also different levels of error correction which will also heavily affect data density
https://www.qrcode.com/en/about/version.html
@Mooclown I think our calculations were using 177 x 177 codes, the largest ones, which come to think of it would probably hate being within 2 centimeters
@Mooclown good question, no! so if you printed double sided you could actually fit 630 kilobytes on a sheet of paper, nice