Base32 vs Base64: when bigger overhead is the better choice
Base64 for machine-to-machine data exchange. Base32 for anything a human will type, read, or transcribe. The overhead difference (33% vs 60%) is negligible for the small payloads (a few dozen bytes) where human readability matters.
Base64 packs 6 bits per character and expands data by 33%. Base32 packs 5 bits per character and expands data by 60%. Base32 is larger, but the RFC 4648 alphabet excludes the digits 0, 1, 8, and 9 and is commonly handled case-insensitively. It still contains letters such as I, L, and O, so it reduces some transcription errors rather than eliminating lookalikes. For data that humans type or read aloud, the extra overhead can be worth that trade.
By TechCompare · Updated
How this is calculated
Base32 is used for OTP secrets (the 16-character codes you type into Google Authenticator), product license keys, and recovery codes. The RFC 4648 Base32 alphabet excludes 0, 1, 8, and 9 to avoid confusion with O, I/l, B, and g/q. Base64's alphabet includes letters in both cases, digits, +, and /, making it error-prone for human transcription. If a user is going to type the encoded value, Base32. If machines are exchanging it, Base64.
Verdict
The choice hinges on who reads the output. Base64 carries 6 bits per character at 33% overhead but mixes upper and lower case with + and /, which humans mistype. RFC 4648 Base32 drops to 5 bits per character for 60% overhead and excludes the digits 0, 1, 8, and 9, but it still contains letters such as I, L, and O. That trade makes Base32 common for OTP secrets and recovery codes.