255 in binary
The decimal number 255 written in binary is 11111111. In hexadecimal it is FF, and in octal 377.
| Base | Value |
|---|---|
| Decimal (base 10) | 255 |
| Binary (base 2) | 11111111 |
| Hexadecimal (base 16) | FF |
| Octal (base 8) | 377 |
How 255 converts to binary
Binary is base 2, so each place is worth twice the one to its right: 1, 2, 4, 8, 16, and so on. Adding up the place values that have a 1 gives back the decimal number:
128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255
That is why 255 in decimal is 11111111 in binary: it is exactly the set of powers of two that add up to 255. To get the hexadecimal form, group the bits into fours from the right and write each group as one hex digit, which gives FF.
Convert any number
Type any value and watch all three bases update live in the binary converter, or read the theory behind it in the lessons on binary numbers and hexadecimal.
Want to build the circuit that does this? Open the lab and wire up an adder, or follow the free course from a single transistor up to an 8-bit CPU.
Open the binary converter →Frequently asked
What is 255 in binary?
255 in binary is 11111111. That is the sum of the powers of two 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1, which add up to 255.
What is 255 in hexadecimal?
255 in hexadecimal is FF. You get it by grouping the binary digits 11111111 into fours from the right and writing each group as one hex digit.
How many bits is 255?
255 needs 8 bits in binary (11111111). It fits in a single 8-bit byte.