Number base converter

Type a number in any base and see it in binary, octal, decimal and hexadecimal.

Binary (base 2)Octal (base 8)Decimal (base 10)Hexadecimal (base 16)

Bases in programming

Binary (base 2): how computers store everything. Prefix 0b in many languages.
Octal (base 8): Unix permissions like 755. Prefix 0o (or a leading 0 in C).
Decimal (base 10): everyday numbers.
Hexadecimal (base 16): colors, memory addresses and bytes. Two hex digits make one byte. Prefix 0x.

Numbers of any size are supported, using JavaScript's BigInt.

What is 255 in hex?

FF. It's 11111111 in binary, the largest value one byte can hold.

Can I paste numbers with 0x or 0b prefixes?

Yes. Prefixes, spaces and underscores are ignored.