Binary/Hex/Decimal Converter

The Binary/Hex/Decimal Converter is a free number base converter that translates numbers between binary, octal, decimal and hexadecimal simultaneously — type a value once in any base and instantly read its equivalent in all four. It covers the everyday conversions developers need: binary to decimal, hex to decimal, decimal to binary and every other pairing between the four bases, without switching tools or doing the arithmetic by hand.

It accepts the prefixes you'd actually type in code — 0b for binary, 0o for octal, 0x for hexadecimal — plus underscore digit separators (like 1_000_000) for readability, so you can paste a literal straight out of your source code. That makes it useful well beyond homework: working out a bitmask, decoding a color value like #FF6600 into its decimal RGB channels, reading a Unix file permission (like 0755) in binary to understand exactly which bits are set, or converting a memory address between hex and decimal while debugging. It's also a quick way to sanity-check a subnet mask, verify a checksum digit, or translate an ASCII character code between its decimal and hexadecimal form when working with raw byte data or a binary file format.

Because the converter is built on JavaScript's BigInt rather than ordinary numbers, it converts arbitrarily large integers exactly, with no precision loss past 2⁵³ — the point where regular floating-point numbers start silently rounding. That makes it reliable for 64-bit values, large hash fragments and cryptographic key material where a single incorrect digit would matter.

Every keystroke is validated against the selected base's allowed digits, so a stray 'a' typed into a decimal field or an '8' typed into an octal field is flagged immediately, rather than producing a silently wrong conversion downstream.