How binary converter works
Numbers can be written in any base. Computers most often use base 2 (binary, digits 0 and 1), base 8 (octal, 0-7), base 10 (decimal, our everyday system), and base 16 (hexadecimal, 0-9 and a-f). Each base is just a different way of grouping the same value; conversion works by parsing the input in its source base and re-formatting it in the target base.
Enter a value, choose the base it is written in (from), and the base you want (to). The converter validates the digits against the source base — for example it rejects "102" as binary because 2 is not a binary digit — then parses and re-formats. It always shows the value in all four bases so you can see the whole picture at once.
Hexadecimal is common in programming for memory addresses and color codes, binary for bit-level work, and octal for Unix file permissions. This converter handles positive integers in any of the four bases and is a quick reference for translating between them.