Format & Convert
Number Base Converter
Binary, octal, decimal, hex and base 36 for numbers of any size, with two’s complement.
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About the Number Base Converter
Convert integers between binary, octal, decimal, hexadecimal and base 36. It uses arbitrary-precision arithmetic, so 128-bit and larger numbers convert exactly, and shows the two’s complement bit pattern of negative numbers at 8, 16, 32 and 64 bits.
How to use it
- Choose the base of your input.
- Type the number (0x, 0b and 0o prefixes and underscores are fine).
- Copy any of the converted values.
Frequently asked questions
- Is there a size limit?
- No practical limit: the converter uses BigInt, so very large numbers are exact.
- How do I see a negative number in binary?
- Enter it in decimal with a minus sign; the two’s complement patterns for 8, 16, 32 and 64 bits are listed when the value fits.
- Is anything uploaded?
- No. Everything runs in your browser tab with JavaScript. Nothing you enter is uploaded, logged or stored, and the page works offline once loaded.