Number Base Converter
Convert numbers between binary, octal, decimal, hex, and any custom base from 2 to 36. Supports bigints. Real-time, offline.
About this tool
Convert any number between binary (base 2), octal (base 8), decimal (base 10), hexadecimal (base 16), and any custom base from 2 to 36. Type in any field, pick the source base, and all four standard conversions plus your custom base appear instantly. Handles big integers up to about 50 digits so you can crunch cryptography-sized or math-class-sized numbers without losing precision. Each output has its own copy button, and signed integers show a separate two's complement row for binary and hex. Everything runs locally in your browser, works fully offline, and never sends your numbers anywhere.
Details
- Category
- Utilities
- Version
- 1.0.0
- Size
- 24 KB
- Updated
- Jun 2026
Frequently Asked Questions
What bases are supported?
Binary (base 2), octal (base 8), decimal (base 10), hexadecimal (base 16), and any custom base from 2 to 36. Bases above 36 would need more than alphanumeric characters to represent, so we stop there.
Why are some conversions so long?
Base conversions are exponential. A 10-digit decimal number becomes about 33 digits in binary and 27 in hex. Big integers are intentional — you can crunch crypto-sized values without losing precision.
Does it handle negative numbers?
Yes. When the input parses as negative, all conversions are shown with a minus sign. For binary and hex specifically, the two's complement row shows the same magnitude represented as a fixed bit-width (the next multiple of 4 that fits the absolute value).
Is there a size limit?
No hard limit, but the tool is built for practical math. Numbers up to about 50 decimal digits convert instantly. Push it to 200+ digits and your browser may slow down — that's just JavaScript BigInt doing its thing.
Is my data sent anywhere?
No. All parsing and conversion happens in your browser. Nothing is uploaded, so it works fully offline.
