Number Base Converter: Binary, Octal, Decimal and Hex

What is this tool?

Enter a number in any base and see it in binary, octal, decimal, hexadecimal, and a base of your choice at the same time. Numbers can be as large as you like, prefixes such as 0x and 0b are detected automatically, and the bit table shows two's-complement patterns for signed values.

Conversion uses arbitrary-precision integers (BigInt), so even 100-digit numbers convert exactly with no rounding. Negative numbers keep their minus sign in every base.

Two's complement is how computers store signed integers: -1 in 8 bits is 11111111. The table shows whether a value fits each width and its exact bit pattern.

To convert text into binary or hex bytes, use the Encoder / Decoder instead — this tool converts numeric values.

How to use the Number Base Converter

1. Type a number, or paste one with a 0b, 0o, or 0x prefix.
2. Choose its base if it wasn't detected automatically.
3. Read the result in binary, octal, decimal, hex, and a custom base from 2 to 36.
4. Copy any value, and check the two's-complement table for 8-, 16-, 32-, and 64-bit patterns.

Examples

255

Binary 11111111 · Octal 377 · Hex FF

Frequently asked questions