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> The reason for representing Health Cards using Numeric Mode QRs instead of Binary Mode (Latin-1) QRs is information density: with Numeric Mode, 20% more data can fit in a given QR, vs Binary Mode. This is because the JWS character set conveys only log_2(65) bits per character (~6 bits); binary encoding requires log_2(256) bits per character (8 bits), which means ~2 wasted bits per character

https://spec.smarthealth.cards/#encoding-chunks-as-qr-codes

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Whoever wrote this makes my head hurt.

If you were using binary storage, you wouldn't use "the JWS character set" (aka base64). You'd store it directly and have 0 wasted bits.

Also, they're not acknowledging the bits wasted by their current system. Numeric mode in QR codes spends 3.33 bits per digit. At two digits per character, they're spending 6.67 bits to store only 6 bits of information.

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