Twos Complement Calculator

Twos complement is the standard way computers store signed integers. A negative value is the bit pattern you get by adding 2 to the power of the bit width, so -1 in 8 bits is 11111111.

Write the positive value in binary, flip every bit, then add 1. The result is the twos complement form, which this tool computes for you at any width.

An n-bit signed integer runs from minus 2 to the power n minus 1 up to 2 to the power n minus 1, minus 1. For 8 bits that is -128 to 127, so there is one more negative value than positive.

It is the same bit pattern read as a plain unsigned number. For -1 in 8 bits the pattern 11111111 equals 255 when treated as unsigned.

Yes. Enter a bit pattern of the chosen width and the tool reads the top bit to decide the sign and returns the signed integer it represents.