Octal to Hexadecimal Converter

Octal is the base-8 number system, using digits 0–7. Because each octal digit maps exactly to 3 binary bits, it was historically popular for compactly displaying binary data on systems with word sizes divisible by 3. Today its main practical use is Unix/Linux file permissions, expressed as three-digit octal numbers like 755.

Hexadecimal is the base-16 number system, using digits 0–9 and letters A–F. Each hex digit maps exactly to 4 binary bits (a nibble), so two hex digits represent a full byte. This makes hex the standard way to write memory addresses, color codes, and hashes compactly.

Octal and hexadecimal don't convert directly digit-by-digit, since 8 and 16 don't share a common bit-grouping — instead, convert octal to binary first (3 bits per digit), then regroup those bits into 4-bit nibbles to read off the hex digits. For example, octal 312 expands to binary 011001010 (9 bits); padding to a multiple of 4 gives 000011001010, which regroups into nibbles 0000 1100 1010 — that's 0, C, A, or CA once the leading zero is dropped.