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.

What are hexadecimal and binary representations?

Binary writes a value in base 2 and hexadecimal in base 16, where one hex digit stands for exactly four bits, so a byte is always two hex characters (0x00–0xFF). Hex is how hashes, colours, memory addresses and raw bytes are usually shown, and Base16 encoding (RFC 4648) is simply hex applied to a byte sequence.

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.

References