Number Base Converter
Type a number in binary, decimal, hexadecimal or octal: every other base updates live. Very large numbers are supported.
Type a number in any base
Decimal value
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About number bases
A base tells you how many different digits are used: 10 in decimal (0 to 9), 2 in binary (0 and 1), 16 in hexadecimal (0 to 9 then A to F). Computers work in binary; hexadecimal is a compact way to write it, one hex digit being exactly 4 bits.
Features
- Four synced bases: decimal, hexadecimal, binary, octal
- Any base: from 2 to 36
- Big numbers: no size limit, no loss of precision
- Prefixes accepted: 0x, 0b, 0o; spaces and “_” ignored
- Two’s complement on 8, 16, 32 or 64 bits for negative numbers
- Digit grouping by 4 (binary, hex) or by 3 (decimal, octal)
How to use
- Step 1: type your number in the field for its base
- Step 2: read the conversion in the other fields
- Step 3: pick another base or a two’s complement width if needed
Examples
- 255 = FF in hex = 1111 1111 in binary = 377 in octal
- 0x1F = 31 in decimal
- -1 in 8-bit two’s complement = 1111 1111 (0xFF)
- Unix permissions: 755 in octal = 111 101 101 in binary
Use cases
- Programming, bit masks, registers and protocols
- CSS colours (#FF8800 → 255, 136, 0)
- Computer science and electronics classes
- Memory addresses and hex dumps
Privacy
Everything is computed in your browser: the data you enter is never sent anywhere and we never have access to it. Internal data can be pasted safely.