Octal to Base64

Octal to Base64 Converter

Convert bytes written in octal (base 8) to Base64 and decode Base64 back to octal byte values. Octal is less common than hex today, but it is still everywhere in Unix tooling, C string escapes, and older documentation, so it's handy to be able to jump straight to Base64.

Where octal bytes come from

• od – the classic Unix dump tool prints octal by default: echo -n Hello | od -b shows 110 145 154 154 157, exactly the sample above.
• C, Python, and shell escapes – string literals like "\110\145\154\154\157" or printf '\110\151' use three-digit octal escapes.
• Legacy protocols and textbooks – older networking RFCs, PDP-11 era material, and some embedded datasheets list byte values in octal.
• File permissions – modes like 755 are octal numbers, though they are integers rather than byte strings.

How the conversion works

Each octal token is parsed as one byte (0 to 377), the byte sequence is grouped into 24-bit blocks, and each block becomes four Base64 characters. 110 145 154 154 157 is 72, 101, 108, 108, 111 in decimal – the letters Hello – and encodes to SGVsbG8=. In the other direction, Pz8= decodes to 077 077, two question marks.

Input rules and options

Separate the values with spaces, commas, semicolons, or new lines; 0o prefixes and separated backslash escapes such as \110 \145 are also understood. Every token must contain only the digits 0–7 and fit in a byte. Digits 8 or 9 trigger a clear error message, which often reveals that the data was actually decimal.

For output, URL-safe Base64 is available when encoding, and decoded bytes are always padded to three digits and can be separated by spaces, commas, or new lines. For other notations see Hex to Base64 and Binary to Base64.