Number base converter
Convert between binary, octal, decimal and hexadecimal.
BIN11111111
OCT377
DEC255
HEXFF
Type a number, pick its base, and read it instantly in all four bases — with one-click copy for each.
Frequently asked questions
Can I paste values with prefixes like 0x?
Yes — 0x, 0b and 0o prefixes are stripped automatically before conversion.
What is the maximum value?
Anything within JavaScript's safe integer range — over 9 quadrillion, far beyond everyday use.