Number base converter
Convert a number between binary, octal, decimal and hex.
Read a hex colour as decimal, a permission mask as binary, or a 64-bit identifier in whatever base a log printed it. The conversion runs through BigInt rather than ordinary numbers, which matters more than it sounds: past about nine quadrillion an ordinary number silently rounds, and a 64-bit id is exactly the kind of thing people bring to a base converter.
How to use it
- Type the number.
- Say which base it is already in.
- Read it in every other base.
Why use this tool
Completely private
Everything runs inside your browser. Your files and text are never sent to a server.
Free, with no limits
No sign-up, no watermarks and no cap on how many times you can use it.
Instant results
There is no upload or queue to wait for, so results appear as fast as your device can work.
Works on any device
Runs in any modern browser on phone, tablet or desktop. Nothing to install.
Frequently asked questions
- What happens with very large numbers?
- They stay exact. A Telegram chat id or a snowflake id is past the point where a normal JavaScript number starts rounding, so the conversion uses arbitrary-precision integers instead.
- Why is my input rejected?
- Because it contains a digit the base does not have. There is no 2 in binary and no g in hex. Refusing is better than guessing at what was meant.
- Can I convert negative numbers?
- Yes, with a leading minus. Spaces and underscores in the input are ignored, so 1010_1010 and de ad both work.
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