Binary, Hex, Decimal & Octal Converter
Convert a whole number between binary, octal, decimal and hexadecimal. Type in any one box and the other three update live — nothing is uploaded, everything runs in your browser.
Your input stays in your browser — nothing is sent anywhere.
How to use the number base converter
Type a whole number into any of the four boxes — decimal, binary, octal or hexadecimal — and the other three convert instantly. There is no button to press and nothing leaves your device.
A number base (or radix) is just how many distinct digits you count with before carrying over. Decimal is base 10 (digits 0–9), the everyday number system. Binary is base 2 (digits 0 and 1), the language of computers. Octal is base 8 (digits 0–7), and hexadecimal is base 16, which extends the digits with the letters A–F to stand for 10 through 15.
For example, the decimal value 255 is 11111111 in binary, 377 in octal and FF in hexadecimal — four different ways of writing exactly the same quantity. You can paste hex with a leading 0x, binary with 0b or octal with 0o, in upper or lower case, and the converter handles it.
Everything runs in your browser — the numbers you type are never uploaded.
Common questions
Does it handle very large numbers? Yes. The converter uses exact big-integer math, so even long hexadecimal or binary strings convert without losing precision — unlike many calculators that round once a value passes about 15 digits.
Why does hexadecimal use letters? Base 16 needs sixteen distinct digit symbols. After 0–9 there are only ten, so the letters A, B, C, D, E and F stand in for the values 10 through 15.
Can I convert negative numbers or decimals? This tool converts non-negative whole numbers. Fractions and negative values (and two's-complement representations) are not supported.
Is anything saved or uploaded? No. The tool is fully client-side — your input never leaves your browser and nothing is stored.