Frequently Asked Questions
Everything you need to know about the Two's Complement Calculator.
What is two's complement?
A method of representing signed integers in binary where negative numbers are formed by inverting the bits of the positive value and adding 1.
Why do computers use two's complement instead of a sign bit?
Because it lets the same binary addition circuitry work for both positive and negative numbers, with no separate subtraction logic needed.
How do I convert a negative decimal to two's complement?
Write the magnitude in binary, invert every bit, then add 1. The calculator shows each of these steps.
What bit widths are supported?
4-bit, 8-bit, 16-bit, and 32-bit.
What happens if my number is out of range?
The calculator shows an overflow message with the valid range for the selected bit width, e.g. -128 to 127 for 8-bit.
How is the sign determined in two's complement?
The leftmost (most significant) bit: 0 means non-negative, 1 means negative.
Can I convert binary back to decimal?
Yes, switch to Binary โ Decimal mode and enter a two's complement bit string.
What is the range for an 8-bit signed number?
-128 to 127.
Is my data stored?
No; all conversion happens locally in your browser.
Is it free?
Completely free, no sign-up or limits.