Decimal Converter

Repeatedly divide the number by 2 and write down the remainders, reading them from last to first. For 13: 13÷2=6 r1, 6÷2=3 r0, 3÷2=1 r1, 1÷2=0 r1 → 1101. Or subtract the largest powers of 2 (128, 64, 32, 16, 8, 4, 2, 1) that fit and mark a 1 for each one used.

Repeatedly divide by 16 and record the remainders from last to first, using A-F for 10-15. For 250: 250÷16=15 r10 (A), 15÷16=0 r15 (F) → FA, which is 0xFA. For 255 it is 0xFF. Every two hex digits represent one byte.

Repeatedly divide by 8 and read the remainders backwards. For 255: 255÷8=31 r7, 31÷8=3 r7, 3÷8=0 r3 → 377, written 0o377. Octal is most commonly seen in Unix and Linux file permissions, where 0o755 means owner rwx (7), group rx (5), and others rx (5).

For humans, binary → hex is the easiest because each hex digit is exactly four bits (0b11111111 = 0xFF). Decimal → binary works by dividing by 2. For any other combination, or for large numbers, just use this tool — it auto-detects the input base (binary, decimal, hex, or octal) and shows every representation instantly, with exact BigInt precision for values far beyond a normal calculator.

There is no practical limit. The tool uses arbitrary-precision BigInt arithmetic, so it converts values with dozens or even hundreds of digits exactly — no rounding, no overflow. The only constraint is the length of the binary output you want to read.

Everything in a computer — text, images, sound, programs — is stored as binary numbers. A character is a code point (e.g. "A" is 65), a color is three numbers (red, green, blue), and an instruction is an opcode. Converting between decimal, hex, and binary is how you inspect and debug that underlying data, which is exactly why developers reach for converters daily.

Yes — completely free, no registration, and 100% private. All conversion happens locally in your browser; your numbers are never sent to any server. The tool works offline after the page loads.