Decimal to Binary Converter

About the Decimal to Binary Converter

Binary is how computers represent numbers internally, as sequences of bits. This tool converts decimal numbers to binary using arbitrary-precision arithmetic, so even very large values convert exactly. Put one number per line to convert a whole list.

It is useful for learning number systems, working with bit flags and masks, and reading low-level documentation. To go the other way, use Binary to Decimal; to see a number in every base, the All Base Converter.

The arithmetic is repeated division by two: divide, note the remainder, repeat with the quotient, then read the remainders from the last one back to the first. That is why the rightmost bit tells you whether a number is odd, and why doubling a value is the same as appending a zero. Each position to the left is worth twice the one before it, so eight bits reach 255 and sixteen reach 65535.

A negative input keeps its minus sign and only the magnitude is converted, so you will not see a two's complement pattern here. That is deliberate: two's complement only means something once you fix a register width, and this tool does not assume one. If you want the 8-, 16- or 32-bit inverted form, set a width in the Bitwise Calculator. A practical use is working out a bit flag value, since feature number 5 in a bitmask is 100000, or 32 in decimal, and ORing the flags together gives the number you store. For the character bits of a string rather than a number, try Text to Binary.

How to use

1. Paste decimal numbers, one per line.
2. Copy the binary results.
3. Use Binary to Decimal to reverse.