Free Number Base Converter

How this tool computes its result

The converter parses the input string manually rather than using parseInt: it trims and uppercases the value, splits off a leading "-" sign, then walks each character and looks up its position in the string "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" sliced to the source base's digit alphabet, accumulating a BigInt via result = result * base + digitValue. Output conversion reverses this with repeated division and remainder against the target base, prepending each remainder's character. Because the whole pipeline runs on BigInt, there is no floating-point precision loss for arbitrarily large integers, and the tool always also renders binary, octal, and hex alongside your chosen target base.

Worked example

Input "FF" with From base 16 and To base 10: parseBigIntFromBase walks F (15) then F (15) → 15*16+15 = 255n. The converted field shows "255", and the fixed panels below show binary "11111111", octal "377", and hex "FF" — all derived from the same 255n value via toBase.

When not to use this tool

This is an integer-only converter. There is no decimal point or fractional-value handling anywhere in parseBigIntFromBase or toBase, so a value like "3.14" in any base will throw ("Digit "." is not valid for base X") rather than convert. Base range is also hard-capped at 2–36 by the min/max clamps on the base inputs, since 36 is the largest base representable with 0-9 plus A-Z.

Common mistakes

• - Entering a digit that is not valid for the selected source base — e.g. "G" in base 16 or "2" in base 2 — throws `Digit "X" is not valid for base N` instead of silently ignoring it.
• - Leaving the input field blank triggers "Enter a number value." since the trimmed string is checked for emptiness before parsing begins.
• - Assuming lowercase and uppercase letters are both accepted as distinct digits — the input is uppercased before parsing, so case has no effect on the result.

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