What This Tool Does
This tool converts a number between binary, octal, decimal, and hexadecimal, showing all four representations at once and keeping them in sync as you edit any one of them. Everything runs in your browser, there is no server call involved.
How to Convert Between Number Bases
Type a number into any of the four fields, decimal, binary, octal, or hex, and the other three update immediately. Common prefixes like 0x, 0b, and 0o are accepted and stripped automatically for the field they belong to. An invalid value for a field is flagged inline instead of silently breaking the other fields.
The Bit Visualizer and Signed Values
The bit pattern panel renders the number's binary form as individual, color-grouped bits, with byte boundaries labeled. Choosing a fixed bit width, 8, 16, 32, or 64, shows whether the value fits within that width and its two's complement signed interpretation, letting you see how a number would actually be stored and interpreted in a fixed-width integer type.
Why BigInt Matters for Large Numbers
JavaScript's built-in Number type loses precision above 2^53, which is easy to hit with large hex or binary values. This tool uses BigInt for every conversion internally, so precision is exact regardless of how large the number is, unlike naive base-conversion tools built on floating-point parsing.
Common Uses for a Base Converter
Debugging a bitmask or flags value, converting a hex color code to decimal or binary, checking how a number would be represented in a fixed-width signed integer type, and translating a value into ready-to-paste literal syntax for a specific programming language are all common uses for this tool. It works as a binary to decimal converter, a hex to decimal converter, a decimal to binary converter, and a hex to binary converter, as a general number base converter online and binary octal hex converter covering base 2 8 10 16 converter needs, a bigint base converter that never loses precision, and a two's complement calculator for signed bit widths.