Number Base Converter

Binary, octal, decimal and hexadecimal are always shown, and the custom slider covers every base from 2 to 36. Above base 10 the digits continue with the letters a to z.

Yes. Conversion uses arbitrary precision integers rather than normal JavaScript numbers, so values far beyond the safe integer limit convert exactly with no rounding.

No. Prefixes such as 0x, 0b and 0o are stripped automatically, so you can paste a literal straight out of source code without editing it first.

Hexadecimal allows 0 to 9 and a to f only. A letter beyond f, or a stray character such as a comma or an h suffix, makes the value invalid for that base.

Not currently. It handles non-negative integers. For negative values in binary, what you usually want is a two's complement representation at a fixed bit width, which is a different question.

Integers only. Fractional conversion between bases produces repeating expansions in most cases and needs a precision setting, so it is deliberately out of scope here.

One hexadecimal digit maps exactly to four bits, so a byte is always two digits. That makes colours, memory addresses, and byte-level data far easier to read than the equivalent binary.

Yes, completely free with no sign-up, like every tool in the Pinkontin developer toolbox.