Number Base Converter

Runs in browser Utilities

Convert integers of arbitrary size between bases with BigInt precision, including negative numbers and custom digit alphabets.

Privacy: This tool runs entirely in your browser. Your input never leaves your device.

How to use Number Base Converter

  1. Type the number and select its base.
  2. Select the target base (or enter a custom alphabet).
  3. Read the result and the common-base breakdown.

Number Base Converter features

  • Any base from 2 to 36, or a custom digit alphabet
  • Arbitrary precision with BigInt — no rounding at any size
  • Negative numbers, 0x/0b/0o prefixes, digit separators
  • Shows binary, octal, decimal and hex alongside the target base
  • Positional expansion (1×16² + 10×16¹ + …) for learning and checking
  • Optional digit grouping

Number Base Converter example

Hex to binary

Input:

FF (base 16 → base 2)

Output:

11111111

Frequently asked questions about Number Base Converter

How large can the number be?

Any size — conversion uses BigInt, so thousands of digits are converted exactly without floating-point rounding.

Are negative numbers supported?

Yes, a leading minus sign is kept. Use the Decimal/Binary/Hex tool for two's complement representations of negatives.

Can I use prefixes like 0x?

Yes. 0x, 0b and 0o prefixes are accepted when they match the selected base; spaces, commas and underscores between digits are ignored.

What is a custom alphabet?

A string of symbols that defines the digits (0 to base−1). For example "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567" gives RFC 4648 Base32 digits. It must contain at least as many unique symbols as the base.