Number base converter
Convert between binary, octal, decimal, and hexadecimal.
Converts live as you type. Nothing is uploaded.
How to use this tool
Type a number into any one of the four boxes. The other three update at once to show the same value in that base.
How bases work
A base is how many distinct digits a number system uses. Decimal uses ten, binary two, octal eight, and hex sixteen. The same quantity can be written in any base; only the digits change, not the value.
value = parse in source base, then format in each target base
A real example
You are reading a permission value shown in octal and a color byte shown in hex. Dropping each into this tool gives the plain decimal value so you can reason about them together.
Common questions
Why did a box turn up an error?
The characters did not fit that base, for example a 2 in a binary field. Only valid digits for the base you type into are accepted.