Best Free Number Base Converter
Convert between binary, octal, decimal and hex with four live-synced fields, plus a text-to-binary mode.
100% free
No signup
No watermark
Files processed in memory, never stored
✨
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How it works
- Pick a field. Click the binary, octal, decimal or hex box.
- Type your number. The other three bases update live as you type; bad digits are flagged.
- Copy a value. Click any field to copy it. Everything runs in your browser.
About this tool
Convert a whole number between binary, octal, decimal and hexadecimal without anything leaving your machine. Type into any one of the four fields and the others update instantly. Invalid digits for a base are flagged rather than silently corrupting the result, and arbitrary-size numbers are handled with BigInt, so a 64-bit mask or a long hex value converts exactly. Click any field to copy it. The Advanced options add a text ↔ binary mode that turns words into space-separated 8-bit bytes (UTF-8) and back.
What people use it for
- Read a hex colour, mask or address in decimal
- Turn a permission/flag value into binary bits
- Convert decimal to hex for code or config
- Encode text as binary bytes (and decode it back)
Frequently asked questions
No. Type into any of the four fields and the other three update live as you type.
The tool flags it (for example a 2 in a binary field, or a g in hex) and leaves the other fields untouched instead of producing a wrong number.
Yes. Conversion uses BigInt, so large values like 64-bit masks or long hex strings convert exactly without precision loss.
Click the field you want and its value is copied to your clipboard, with a brief "Copied!" confirmation.
In Advanced options you can type text and see it as space-separated 8-bit bytes (UTF-8), or paste binary bytes and read them back as text.
No. All conversion happens in your browser, so nothing you enter is sent to or stored on a server.
Yes — Number Base Converter is completely free, with no watermark on the output and no credit card required.
Yes. It runs in your browser, so Number Base Converter works on phones and tablets as well as desktop — there is no app to install.
No. Number Base Converter works with no signup at all; an optional free account only exists to unlock higher usage limits.
Usually just a few seconds for a typical file — Number Base Converter starts working the moment you give it your input.