Octal Converter

What is the Octal Converter?

This converter links four number-base fields together — decimal, binary, hexadecimal and octal. Type a value into any one of them and the other three update instantly, so you always see the same number written in all four common bases at once. It is aimed at anyone working with octal notation, such as Unix file permission modes, but you can just as easily start from any of the other three bases.

How to use it

1. Click into the field for the base you already have a number in.
2. Type the value using only the valid digits for that base (binary: 0-1, octal: 0-7, decimal: 0-9, hexadecimal: 0-9 and A-F).
3. Read the converted value straight off the other three fields — there's no separate "convert" button needed.

Binary is the native language of digital circuits, where every value is stored as a sequence of 0s and 1s; hexadecimal is a compact shorthand for binary that programmers use for memory addresses, colour codes and byte values, since each hex digit maps neatly to exactly four binary digits; octal, base 8, shows up in older Unix file permission notation like chmod 755. This tool supports arbitrarily large whole numbers, converting internally with exact big-integer arithmetic rather than floating-point math, so results stay accurate even for very long binary strings.