About this tool
This converter turns a base-10 number into its base-2 representation. For positive numbers it repeatedly divides by two and reads the remainders; the result is the sequence of 0s and 1s a computer would store.
Enter a decimal number and the binary updates live. Leave the width unset for the shortest exact representation of a non-negative number, or pick 8, 16 or 32 bits to pad the output and to represent negative numbers in two's complement. Turn on 4-bit grouping to read long values more easily, and copy the result with one click.
Large integers are converted exactly using arbitrary-precision math, all locally.
Frequently asked questions
How are negative numbers handled?
Negative numbers require a bit width, because two's complement is defined relative to a fixed number of bits. Choose a width and −1 becomes 11111111 in 8 bits, −128 becomes 10000000, and so on.
Is there a maximum number?
No — conversion uses arbitrary-precision integers, so even numbers far beyond 64 bits convert exactly without rounding.
What does 4-bit grouping do?
It inserts a space every four bits (one nibble), so 11110000 reads as 1111 0000. It's purely visual and makes long binary values easier to scan; it doesn't change the value.