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File & Format Converters · Free tool

Number Base Converter

Convert any number between binary, octal, decimal, and hexadecimal at the same time. Clean UI, no ads.

Updated April 2026

Type in any field — the others update live. Supports arbitrarily large numbers via BigInt.

What it does

A free number base converter with binary, octal, decimal, and hexadecimal on screen at the same time. Type in any one field — the others update instantly. Uses BigInt, so arbitrarily large numbers work without precision loss.

Useful for low-level debugging (memory addresses in hex, bitmasks in binary), CSS color math (hex ↔ decimal channels), permissions (octal file modes like 755), and CTF/puzzle work. Prefixes like 0x, 0b, and 0o are accepted in the matching field.

How to use it

  1. Type a number in any field — binary, octal, decimal, or hex.
  2. Watch the other three update live.
  3. Tap Copy next to any field to grab that representation.
  4. Negative numbers and BigInt-sized values are supported.