Number Base Converter

Convert numbers between binary, octal, decimal and hexadecimal, one per line, with big-integer support.

Numbers
Converted
Runs locally in your browser

About the Number Base Converter

This converter changes numbers from any of the four common bases to any other: binary (base 2), octal (base 8), decimal (base 10) and hexadecimal (base 16). It uses arbitrary-precision integers, so very large values, well beyond what a normal number can hold, convert exactly rather than losing precision. Convert a whole column at once by putting one number per line.

Options add a base prefix (0x for hex, 0b for binary, 0o for octal) and group the digits for readability, four at a time for binary and hex, three for decimal. Negative numbers are supported. For a single number shown in every base at once, use the All Base Converter.

Common uses are reading a hex colour or memory address in decimal, working with binary flags, and following low-level documentation. For converting text to its byte values rather than a number, the Hex Encode and Text to Binary tools are what you want.

How to use

  1. Paste numbers, one per line.
  2. Choose the from and to bases.
  3. Toggle prefixes and grouping, then copy the result.

Common questions

Does it handle very large numbers?
Yes. It uses arbitrary-precision integers, so numbers far beyond 64 bits convert exactly.
Can it convert several numbers at once?
Yes, one per line; each is converted independently.
Are negative numbers supported?
Yes. A leading minus is preserved; the magnitude is converted.
What about fractional numbers?
This tool converts integers. For a decimal fraction, convert the integer and fractional parts separately.