Number Base Converter — Binary, Octal, Decimal, Hex & Any Base

How number bases work

A base (or radix) is how many digit symbols a number system uses before it rolls over to the next place. Decimal is base 10 (0–9); binary is base 2 (0–1); hexadecimal is base 16 (0–9 then a–f). The same value just wears different clothes: 255 in decimal is 11111111 in binary and ff in hex — one quantity, three spellings.

The conversions nobody else bothers with

Most converters only do the popular pairs (decimal↔hex, decimal↔binary). This one shows every common base at once and adds an arbitrary base 2–36 field, so the awkward directions are right there: octal → hex, hex → octal, decimal → base 32, base 36 → binary. No two-step dance through decimal.

Gotchas worth knowing

• Big numbers stay exact. This tool uses arbitrary-precision integers, so a 40-digit number converts without the rounding errors that hit tools relying on standard floating-point.
• Integers only. Base conversion here covers whole numbers. Fractional values (like 0.1 in binary) are a different problem with their own rounding traps.
• Prefixes are optional. You can paste 0xff, 0b1010 or 0o755 with the matching input base — the prefix is stripped automatically.
• Letters are case-insensitive. FF and ff are the same hex value; output is lowercase.

Frequently asked questions

What is 3735928559 in hex?

It's deadbeef — a famous "magic number" often used as a placeholder in memory. Try it: the decimal default above converts straight to it.

How do I convert octal to hex directly?

Set the input base to 8, type your octal number, and read the Hex (16) row. There's no need to go through decimal yourself — every base updates at once.

What's the largest number I can convert?

There's no practical limit. The tool uses arbitrary-precision arithmetic, so hundreds of digits convert exactly.

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