Number Base Converter
Convert a number between bases, with the prefix worked out for you and no precision lost on large values.
What it does
Number Base Converter reads the whole document before doing anything, so what comes back is either valid output or a specific error with the position that caused it — not a partially rewritten file.
When you need it
Usually when something has already gone wrong: a config file an application will not load, an API response that has to be read by a human, or an export that has to be checked before it goes anywhere near a database.
Limits and caveats
Key order is preserved as it appears in the input. Very large documents are limited by your device's memory rather than by an upload cap, since the parsing happens locally. Everything happens in your browser, so the file never leaves your device.
How to use the Number Base Converter
- Paste your content, or load a file.
- The result appears as you type.
- Copy or download the output.
Frequently asked questions
- Does it handle 64-bit values?
- Yes, exactly. The arithmetic uses BigInt rather than JavaScript numbers, which silently lose precision above 2^53 — and a 64-bit hex value is exactly what people paste into a base converter.
- Do I need to type the prefix?
- No. 0x, 0b and 0o are recognised on their own, and if you pick a base explicitly a prefix you pasted with it is ignored rather than treated as digits.
- Do my files get uploaded?
- No. This tool runs entirely in your browser, so the file never leaves your device.