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Number Base Converter

Convert numbers between binary, octal, decimal, hexadecimal and any base from 2 to 36. Arbitrary precision, so large values stay exact.

Binary (2)11111111
Octal (8)377
Decimal (10)255
Hexadecimal (16)ff
Base 3673

How to use the Number Base Converter

  1. Pick the input base. Tell the converter which base your number is already written in.
  2. Type the number. Digits are validated against that base as you type.
  3. Read every base at once. Binary, octal, decimal and hex are shown together.

Frequently asked questions

Does this lose precision on large numbers?
No. Conversion uses arbitrary-precision integers rather than floating point, so values beyond the usual 53-bit safe range convert exactly instead of being silently rounded.
Why does hexadecimal use letters?
Base 16 needs sixteen distinct digits and the decimal system only supplies ten, so A to F stand in for the values ten to fifteen. The same idea extends up to base 36, which uses the whole alphabet.
What is the highest base supported?
Base 36, because that is where the digits zero to nine and the twenty-six letters run out. Anything higher needs an agreed alphabet, and there is no single standard for one.
Can I convert negative numbers?
Yes, a leading minus sign is preserved across every base. Two-complement representations are a different question, since they depend on a fixed word size rather than on the base alone.

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