Base Converter

About the Base Converter

This converts a whole number between the four number bases programmers use — binary (base 2), octal (base 8), decimal (base 10) and hexadecimal (base 16) — showing all four at once. It's an everyday helper for developers reading memory addresses, colour values, bitmasks, file permissions or byte values, and for students learning how number systems work. Enter a value, pick its base, and see the equivalents instantly.

How it works

Your input is validated against the digits allowed in its base (only 0–1 for binary, 0–7 for octal, 0–9 for decimal, 0–9 and A–F for hexadecimal), then parsed to an ordinary integer and re-expressed in each base. Hexadecimal is shown in upper case. It converts the moment you type — no button needed — and flags input that isn't valid for the chosen base.

Assumptions and behaviour

• Works on non-negative whole numbers (integers).
• Hexadecimal digits can be entered in upper or lower case; output hex is upper case.
• Whitespace in the input is ignored, so you can paste spaced or grouped digits.
• All four representations update live from whichever base you enter.

Limitations

• No fractions or negative numbers. It converts whole, non-negative integers; it doesn't handle decimal points (like binary fractions) or signed/two's-complement values.
• Very large numbers lose accuracy. Values beyond the safe integer range (about 9 quadrillion, 2⁵³) can't be represented exactly in JavaScript, so the tool stops rather than showing a wrong answer — split very large values or use a specialist big-integer tool.
• It handles the four common bases (2, 8, 10, 16), not arbitrary bases like base 36.

Privacy

The conversion runs entirely in your browser. Nothing is uploaded or stored.