What this tool does
This converter moves a number between binary, octal, decimal and hexadecimal: type 255 and you get 11111111, 377, 255 and ff at once. You can also paste prefixed values straight from code — 0xFF, 0b1010, 0o17 — and the base is detected for you.
It solves a different problem from the hex tool: that one converts between text and byte strings (turning 你好 into E4BDA0E5A5BD), whereas this one handles the same number written in another base (255 as FF). Bitmasks, registers, memory addresses and protocol fields all need the latter.
How to use
- Step 1: paste the numbers One number per line, with or without a 0b / 0o / 0x prefix. The source base defaults to auto: anything without a prefix is read as decimal.
- Step 2: choose the target base The default output is four columns — bin, oct, dec, hex, tab-separated so they paste into a spreadsheet. Switch the target to a single base for a cleaner result.
- Step 3: add prefixes or grouping Turn on the base prefix to paste values back into code (0xFF, 0b1010), and switch on grouping to make long binary strings readable (1111 1111).
Limits
Integers only. Fractional and floating-point base conversion is out of scope because binary fractions round in ways that invite mistakes, and IEEE 754 bit-pattern decoding is not offered either. No bitwise or mask calculator, and no character-encoding conversion — use the hex or Unicode tools for the latter. A single file is capped at 10MB.
FAQ
Why insist on BigInt?
Because Number stays exact only up to 2^53−1 and silently drops bits beyond it. Parsing 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF (128 bits) with Number yields a wrong decimal value; BigInt keeps it exact.
How is this different from the hex tool?
Different semantics. This tool writes 255 as FF — the same number in another base. The hex tool encodes text 你好 into E4BDA0E5A5BD — a byte string. Use this one for masks and addresses, that one for encoding work.
Are negative numbers supported?
Yes. The sign is preserved (-ff) and is not part of the four-digit grouping.
Can I convert many values at once?
Yes — one value per line and the output lines correspond one-to-one. If a line is invalid the error names the line and the offending character.
Does it support base 32 or custom bases?
No. This tool focuses on the four bases that matter in programming. Base32 and Base58 are alphabets with padding rules rather than number bases, and each has its own tool.
Is the conversion local or server-side?
Entirely in the browser: no request carries your values, so addresses and mask constants never leave the device.