Two's complement of 13
The 8-bit two's complement of 13 is 11110011, the bit pattern that represents -13 (minus 13). Written as a signed 8-bit number, 13 itself is 00001101.
Invert and add 1
Here is the two's complement of 13 at 8 bits, step by step (invert the bits of 13 and add 1):
- Write 13 in 8-bit binary:
00001101. - Invert every bit (the one's complement):
11110010. - Add 1:
11110011.
13 at 4, 8, and 16 bits
| Width | 13 as a signed number | Two's complement of 13 |
|---|---|---|
| 4-bit | — | — |
| 8-bit | 00001101 | 11110011 |
| 16-bit | 0000000000001101 | 1111111111110011 |
A dash means 13 (or its negation) is outside that width's signed range: 4-bit two's complement holds -8 to 7, 8-bit holds -128 to 127, and 16-bit holds -32768 to 32767.
Convert any number
Two's complement is how computers store signed integers, so one adder can both add and subtract. Read the full two's complement lesson, or convert any value at 8, 16, or 32 bits with the two's complement calculator.
Want to see two's complement do real work? Open the lab and wire a subtractor from an adder and inverters, or follow the free course from a transistor up to an 8-bit CPU.
Open the two's complement calculator →Frequently asked
What is the two's complement of 13?
The 8-bit two's complement of 13 is 11110011, the bit pattern for -13. You get it by writing 13 in binary (00001101), inverting every bit (11110010), then adding 1.
How do you write 13 in two's complement?
13 in 8-bit two's complement is 00001101. Positive numbers are identical to plain binary, so no inverting is needed. At 16 bits it is 0000000000001101.
What is 13 in 16-bit two's complement?
13 in 16-bit two's complement is 0000000000001101. Two's complement sign-extends a shorter value by copying the sign bit to the left, so the value is unchanged from its 8-bit form.