Number base converter
Convert numbers between any bases from binary to base 36, one per line.
Number base converter
Every base from binary to base 36 writes the same numbers with different digits. Paste one number per line, pick the source and target base, and each line converts as you type — decimal to hexadecimal by default, but any pair from 2 to 36 works, including base 36 itself, whose digits run from 0 to z.
The input is forgiving about how numbers are usually written. A 0x, 0b or 0o prefix on a line overrides the From base, so a mixed dump of hex and binary literals converts in one pass. Underscores and spaces inside a number are read as digit separators, the way 1_000_000 appears in modern source code, and a leading minus carries through to the result. Empty lines pass through untouched, keeping a converted column aligned with the original. A character that isn't a digit in the source base stops the conversion with a message naming the exact line, rather than guessing at what you meant.
Show all common bases replaces the target base with a one-line summary — decimal, binary, octal and hexadecimal side by side — which is the fastest way to read a magic constant. Uppercase digits writes A–F instead of a–f, and the 0x-style prefix adds 0b, 0o or 0x to bases 2, 8 and 16, ready to paste straight into code. Pad to width left-pads each result with zeros to a fixed number of digits, so a byte reads 00000101 rather than 101 and a converted column lines up. The width is a minimum, never a truncation: a longer number keeps every digit.
The math is exact integer arithmetic at any size: a number with hundreds of digits converts without the rounding that breaks converters built on floating point past 2^53. Everything runs in your browser and nothing is uploaded.