Number Base Converter

Convert numbers between binary, octal, decimal and hexadecimal. Type a value in any base and the other three update live. Each field validates its own digits, so you can't accidentally enter a 2 in binary or a G in hex. Runs in your browser.

FAQ

How do I convert decimal to binary?

Type your number in the Decimal field and the Binary field updates instantly (along with octal and hex). For example, decimal 255 is 11111111 in binary and FF in hex.

What bases does this support?

Binary (base 2), octal (base 8), decimal (base 10) and hexadecimal (base 16). Type a valid value in any one and the other three are computed live.

Does it validate my input?

Yes. Each field only accepts digits valid for its base — the binary field rejects anything other than 0 and 1, and the hex field accepts 0-9 and A-F. Invalid input is flagged rather than silently miscomputed.

Why do programmers use hexadecimal?

Hex is a compact way to write binary: each hex digit maps to exactly four bits, so a byte is two hex digits. That makes colors (#FF8800), memory addresses and byte values much easier to read than long binary strings.

More tools: hex to RGB, Base64 encode/decode, and the full tools list.