Number Base Converter
Convert between decimal, hexadecimal, binary, and octal — all at once, any size integer.
Decimal (base 10)
255
Hexadecimal (base 16)
FF
Binary (base 2)
1111 1111
Octal (base 8)
377
Number base conversion explained
Computers work in binary (base 2). Hexadecimal (base 16) is a compact human-readable form — each hex digit is exactly 4 bits. Octal (base 8) was popular in older systems and Unix file permissions. This converter handles arbitrarily large integers using JavaScript's BigInt, so there's no 32-bit or 64-bit overflow. For individual conversion tools, try Decimal to Binary or Hex to Decimal.
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