Base Converter.
Convert a number between binary, octal, decimal, hexadecimal, and any radix from 2 to 36. Type a value, tell it which base you typed in, and every other base updates live. It uses arbitrary-precision BigInt, so even 256-bit values convert exactly — no floating-point rounding. Runs entirely in your browser.
How positional bases work.
Every base is the same idea. A number is a sum of digits times powers of the base. In decimal, 255 = 2×10² + 5×10¹ + 5×10⁰. In hex, the same value is FF = 15×16¹ + 15×16⁰. In binary it's 11111111. Only the base — the number of distinct digits — changes; the value is identical.
Why programmers love hex and binary. Computers are binary, but long binary strings are hard to read. Hexadecimal is a perfect shorthand: one hex digit maps to exactly four bits, so 0xFF is one byte, 0xFFFF is two. Octal (one digit = three bits) survives mainly in Unix file permissions. Bases above 16 borrow letters — base 36 uses 0-9 then a-z.
Exact, even when huge. JavaScript's normal numbers lose precision above 2⁵³, which silently corrupts large hex values like 64-bit IDs or hashes. This converter uses BigInt, so a 256-bit number round-trips through every base with no rounding error. Negative values are supported with a leading -.