Change Number Base

Every integer base from 2 (binary) through 36. The digits used are 0-9 followed by A-Z, so a base-36 digit can be anything from 0 to Z.

No. The conversion runs entirely in your browser using JavaScript BigInt. There is no fetch, no XHR, and no analytics on your input – the page works fully offline after it loads.

Yes. The tool uses native BigInt for parsing and formatting, so 256-digit hex numbers and multi-thousand-bit decimals convert exactly without precision loss.

Yes. Prefix the input with a minus sign (for example -FF base 16 → -11111111 base 2). The sign is preserved across any base conversion.

The tool rejects the input and names the offending character – for example, “Invalid digit ‘G’ for base 10”. Unlike a plain parseInt, it never silently drops characters it does not recognise.

No. ff, FF, and Ff at base 16 all convert to the same value. The output is always uppercase for clarity.

Yes – below the primary result the tool shows the exact decimal (base 10) value, so you always have a familiar reference point.

Yes. The ⇄ Swap button swaps the two bases and feeds the previous output back in as the new input, making round-trip verification a single click.

They are one-click presets that set the adjacent base field to 2, 8, 10, or 16 respectively. Handy for the 90 % of conversions that only use the common radixes.

Only your browser’s memory. Conversions of thousand-bit numbers finish in milliseconds, and the tool has no artificial character cap on the input.