Number Base Converter
Convert integers between binary, octal, decimal, and hexadecimal live as you type, with full precision for very large numbers.
🔒 Processed locally in your browser
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How to use
- Choose the base your number is currently in from the "From base" dropdown (Binary, Octal, Decimal, or Hexadecimal).
- Type or paste the number into the "Value" box. A leading "-" is supported for negative numbers.
- All four bases update live underneath as soon as you type — there's no button to press.
- Click Copy next to any base to copy that representation to your clipboard.
Features
- Converts between binary, octal, decimal, and hexadecimal simultaneously
- Updates live as you type — no button to press
- Uses native BigInt internally, so precision is never lost even for very large integers
- Supports negative numbers with a leading minus sign
- Validates input per base and shows a clear inline error instead of silently producing garbage
- 100% client-side — your numbers never leave your browser
Frequently asked questions
Does this tool support numbers too large for a normal calculator?
Yes. The converter uses JavaScript's native BigInt type internally instead of regular numbers, so it can handle integers far beyond the 2^53 safe-integer limit without losing precision.
Can I convert negative numbers?
Yes. Just add a leading "-" before the digits, and the negative sign will be preserved across all four base representations.
Does it support decimals or fractions?
No, this tool works with integers only. Decimal points or fractional values aren't supported.
Why am I seeing an error message?
The tool validates that your input only contains digits valid for the base you selected — for example, "9" isn't a valid binary or octal digit, and letters beyond "f" aren't valid hex digits. Fix the invalid characters or switch to the correct base.
Is uppercase or lowercase used for hexadecimal output?
Output is shown in lowercase (e.g. "ff" rather than "FF"), but you can type hex input in either uppercase or lowercase — both are accepted.