Number Base Converter

Binary for bit masks, hexadecimal for colors and memory addresses, octal for Unix permissions, decimal for everything human — sooner or later every developer, student or electronics hobbyist needs to move a number from one base to another. This converter does it in one click: pick the source base, pick the target base, type the value.

Unlike calculators built on ordinary floating-point numbers, this tool uses BigInt arithmetic, so a 256-bit hash, a long IPv6-sized value or a thousand-digit exercise from a textbook all convert exactly, with no rounding and no overflow. Every digit is validated against the source base first, so a stray 8 in an octal value or a g in hex is reported instead of silently producing garbage.

The result panel shows more than the single answer: alongside the converted value you get the same number written in binary, octal, decimal and hexadecimal, which is exactly what you want when debugging bitwise code or checking a checksum by eye.

Everything runs locally in your browser — no server round-trip, no logs, no limits. Preset pages for the popular pairs (binary to decimal, decimal to hex and friends) open the tool with both bases already selected.