Convert numbers between binary, decimal, hexadecimal, and octal, all updating live as you type.
Computers count in binary, base two, using only ones and zeros, while people count in decimal, base ten. Programmers also lean on hexadecimal, base sixteen, and occasionally octal, base eight, because they map neatly onto how bits are grouped. This converter moves a number between all four systems at once, so you can type a value in whichever base you have and instantly read it in the others without doing the arithmetic in your head.
Type a number into the field for the base you know, binary, decimal, hex, or octal, and every other field updates live to show the same value in its own system. You do not press a convert button or pick a direction. Whatever you edit becomes the source of truth and the rest follow along, which makes it easy to sanity-check a value from a few different angles at once.
Each base is just a different way of writing the same underlying quantity, so nothing is approximated. Binary 1010, decimal 10, hex A, and octal 12 are all the exact same number. The tool works with whole numbers, and if you type a digit that is not legal for a base, such as a 2 in a binary field or a G in a hex field, it will not accept it, which quietly stops a common source of mistakes.
Use this instead of a calculator app when you want to see all the representations side by side rather than converting one pair at a time, and instead of memorizing conversion tricks when you just need the answer fast. It is especially handy when you are reading a value in one base from a spec or a register dump and need it in another.
It comes up when you are decoding a color or permission value written in hex, checking a bitmask by eyeing its binary form, reading a file mode in octal, or teaching or learning how number bases relate. Anyone poking at low-level data, embedded work, or a computer-science exercise reaches for a converter like this regularly.
The whole thing runs in your browser with no upload, no account, and no cost. Your numbers stay on your device, and since the math is trivial for any computer, there is no meaningful size limit beyond the very large values your device's memory could theoretically strain on, which everyday numbers never approach.
It is built for whole, non-negative numbers, which covers the vast majority of base-conversion needs. Negative values and decimal fractions involve conventions like two's complement or fixed-point that a simple base converter does not assume for you.
Binary only uses the digits 0 and 1, so a 2 is not a valid binary digit and the field rejects it. The same guard applies to hex, where letters only go up to F, and octal, which stops at 7.
No. Each field already knows its own base, so you type the bare digits and skip the prefixes. You can add those markers yourself afterward if the place you are pasting into expects them.
No, hex letters can be entered in upper or lower case and mean the same thing, so A and a both stand for decimal 10. Output is typically shown in a consistent case for readability.
Its most common modern appearance is Unix file permissions, where a mode like 755 is octal. It groups bits in threes, which historically made it convenient before hex became the norm.
Ordinary integers convert instantly. Extremely long binary strings or huge values could eventually press against your device's memory, but you would need something far beyond a typical register or color value to notice.
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