Link: https://shkspr.mobi/blog/2025/02/why-are-qr-codes-with-capital-letters-smaller-than-qr-codes-with-lower-case-letters/

cross-posted from: https://lemmy.sdf.org/post/59180985

All uppercase text is unreadable and ugly as fuck. But it is what it is.. if you typeset QR codes and can work within a small character set, you’re trapped with all uppers.

So then the question is, what can be safely converted to all uppercase without breaking? Apparently schemes, domain names and email addresses.

But what about the path? Nope, we’re fucked on that:

https://overflow.ocus.top/exchange/webmasters/questions/90339/why-are-urls-case-sensitive

OTOH, sometimes we get lucky

Ultimately a stupid decision by the QR designers indeed. The bulkier the text, the more useful it is to use the smaller char set. But the bulkier it is, the more unpleasant it is to read all uppercase.

No cap?

Compressed uppercase-only text is a electronic communications tradition that has been around for nearly 200 years. The early electrical telegraph systems from 1837 used 5 tri-state needle codes with only uppercase letters, then Morse or Baudot-based codes with only uppercase. Some systems still use ITA2, a 5 bit code with a single case usually rendered as uppercase.

ARRIVED SAFELY STOP WILL WRITE TOMORROW STOP