Base32 Encode / Decode

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Understand Base32 Encode / Decode

Base32 encodes bytes using 32 letters and digits chosen so a person can read them aloud or type them without ambiguity.

How it works

The RFC 4648 alphabet is A–Z plus 2–7. It deliberately omits 0, 1, 8, and 9 because they are easily confused with O, I, and B. Five bytes (40 bits) map to eight characters of five bits each, which makes the output about 60% larger than the input — noticeably worse than Base64's 33%, and the price paid for the smaller alphabet. Padding with = brings the final group up to eight characters, and decoding is case-insensitive.

When to use it

  • Reading or generating the shared secret behind a TOTP code — Google Authenticator, Authy, and 1Password all exchange it as Base32.
  • Encoding a value that will be read off a screen and typed in by hand, or spoken over a phone.
  • Building an identifier for a case-insensitive filesystem, where Base64's mixed case would collide.
  • Working with DNS labels or onion addresses, which are case-insensitive and use Base32 for that reason.

Watch out for

  • There is more than one Base32. RFC 4648 base32 (A–Z, 2–7), base32hex (0–9, A–V), Crockford's Base32, and z-base-32 all exist and none of them interoperate — output that decodes to garbage usually means the wrong variant, not corrupt data.
  • A TOTP secret is random bytes, not text. Decoding one here produces unreadable characters, which is expected: the bytes are the key and they are not meant to spell anything.
  • Like Base64, this is encoding rather than encryption. A Base32 authenticator secret on screen is a live credential in plain sight.

Frequently Asked Questions

When is Base32 used instead of Base64?

Base32 shines where case-insensitivity matters: TOTP authenticator secrets (Google Authenticator, Authy), QR codes that may be uppercased, file system paths on case-insensitive OSes, and checksums for human transcription where zero vs O or one vs l cause errors.

How does Base32 compare to Base64 in size?

Base32 expands data by ~60% (5 bytes → 8 chars) versus Base64's ~33% expansion (3 bytes → 4 chars). The larger overhead is the price for using a smaller, unambiguous alphabet.

What is the Base32 alphabet?

RFC 4648 Base32 uses A–Z and 2–7 (32 characters). It deliberately omits 0 (zero), 1 (one), 8, and 9 to avoid confusion with O, I/L. The = character is used for padding.

How to Use Base32 Encode / Decode

  1. Paste or type your input in the input area above.
  2. The tool processes your input automatically or click Run.
  3. Copy or download the result using the action buttons.
  4. Use Ctrl+Enter to run quickly from the keyboard.