Computers think in binary, programmers read hexadecimal, and people count in decimal — but they are all just different ways of writing the same number. This number base converter instantly translates any value between binary (base 2), octal (base 8), decimal (base 10) and hexadecimal (base 16).
How number bases work
Every number system uses positional notation: each digit's value is multiplied by the base raised to its position. In decimal, 255 means 2×100 + 5×10 + 5×1. In binary, 1011 means 1×8 + 0×4 + 1×2 + 1×1 = 11. The base just changes how many digits are available and how quickly place values grow.
How to use the converter
Type a value, choose the base you entered it in, and the tool shows the binary, octal, decimal and hexadecimal equivalents at once. It accepts optional prefixes like 0x for hex or 0b for binary, and it validates your input so you cannot accidentally enter a digit that does not exist in the chosen base (like a 2 in binary).
Converting by hand
To convert a decimal number to another base, repeatedly divide by the base and read the remainders from bottom to top. To go the other way, multiply each digit by its place value and sum them. Hexadecimal uses A–F to represent the values 10–15, so 255 becomes FF.
Where these bases show up
Binary and hex are everywhere in computing: RGB colors like #FF8800, file permissions, memory addresses, and byte values. Because each hex digit equals exactly four binary bits, hexadecimal is the most convenient shorthand for the raw data a computer actually stores.