Number base converter

Convert a number between binary, octal, decimal, hexadecimal and any base from 2 to 36.

It is written in

How it’s worked out

Place values

Questions people ask

How do I convert binary to decimal?

Multiply each digit by 2 raised to its position, counting from 0 on the right, and add them up. 1011 = 8 + 0 + 2 + 1 = 11.

Why does hex use letters?

Base 16 needs sixteen digits, so after 0–9 it uses A–F for 10–15. One hex digit is exactly four binary digits, which is why programmers like it.