Free Number Base Converter (Binary, Hex)

Convert numbers between binary, octal, decimal, and hexadecimal — all four stay in sync as you type.

How to use / FAQ

Type a number into any of the four boxes — binary, octal, decimal, or hexadecimal — and the other three update instantly. You can paste values with an 0x, 0b, or 0o prefix, and hex is case-insensitive.

What are the 0x, 0b, and 0o prefixes?

They're the conventional markers for hexadecimal (0x1F), binary (0b1010), and octal (0o17) used in most programming languages. You can paste values with or without them — the tool strips the prefix before converting.

How big a number can I convert?

As big as you like. Conversions use arbitrary-precision integers, so values well beyond the usual 64-bit limit stay exact — no rounding or lost digits.

Does it handle negative numbers or decimals?

This converter works with non-negative whole numbers. A minus sign, a decimal point, or digits that don't belong to the chosen base are flagged, and the other fields keep the last valid value.

Is anything sent to a server?

No — every conversion is plain math running in your browser. Nothing you type leaves your device.