Binary Subtraction Calculator

About this calculator

Subtracting one binary number from another follows the same borrowing logic as decimal subtraction, just with only two digits to work with: when a bit needs to borrow, it borrows a value of 2 from the next column instead of 10, since binary is base 2. So 10 (binary, = 2 in decimal) minus 1 requires borrowing, producing 01 (= 1 in decimal). Digital circuits typically avoid direct borrowing altogether and instead compute subtraction by adding the two's complement of the number being subtracted, which turns subtraction into addition — the same operation the hardware already needs for addition.

This calculator is a common reference for computer science and digital logic students working through binary arithmetic by hand before trusting a computer to do it, and for anyone debugging low-level code, checksums, or bitwise operations who needs to verify a subtraction result in binary. Showing both the binary difference and its decimal equivalent side by side makes it easy to catch a borrowing mistake.

Enter two binary numbers and the calculator subtracts the second from the first, in both binary and decimal.