Number Base Converter
Convert between Binary, Octal, Decimal, and Hexadecimal number systems instantly.
Type in any field and the others update automatically.
Type in any field — the others update instantly. Supports positive integers only.
Number base conversion changes how a number is represented.
Base systems:
- Binary (base 2): Uses digits 0 and 1
- Octal (base 8): Uses digits 0–7
- Decimal (base 10): Uses digits 0–9 (everyday numbers)
- Hexadecimal (base 16): Uses digits 0–9 and letters A–F
Examples:
- Decimal 255 = Binary 11111111 = Octal 377 = Hex FF
- Decimal 42 = Binary 101010 = Octal 52 = Hex 2A
- Decimal 10 = Binary 1010 = Octal 12 = Hex A
Common uses:
- Binary: computer memory, digital circuits
- Octal: Unix file permissions
- Hexadecimal: colors (#FF0000), memory addresses
These bases all exist for a reason rooted in how computers work. Binary is the machine’s native language because a transistor is either on or off, one or zero, with nothing between. The trouble is that binary gets unwieldy fast: a single byte is eight digits, like 11111111. Hexadecimal fixes that by packing exactly four binary digits into one hex digit, so that byte becomes a tidy FF.
That four-to-one mapping is why hex turns up wherever programmers need to read binary at a glance. A web color like #FF0000 is three bytes, one each for red, green, and blue: FF means full red, 00 means none of the others, so the result is pure red. Octal works the same way with three bits per digit, which is why Unix file permissions, like 755, are written in it.
How we build and check this converter
This converter runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.