Hexadecimal to Octal Converter

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 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.

Hex and octal don't convert directly digit-by-digit either — convert hex to binary first (4 bits per digit), then regroup those bits into 3-bit groups to read off the octal digits. For example, hex CA expands to binary 11001010 (8 bits); regrouped from the right into 3-bit groups that's 011 001 010, giving octal 312.