About hex and octal

Hexadecimal is base 16 — digits 0–9 then a–f. One hex digit is exactly four bits, so bytes read as tidy two-digit pairs. Colors, memory addresses, and hashes are all conventionally written in hex with a 0x prefix.

Octal is base 8, using digits 0–7. Each octal digit maps to exactly three bits, which is why Unix file permissions like 755 are octal. Code writes it with a 0o prefix.

For example, hex 7c3aed is 37035355 in octal. The converter uses BigInt, so numbers of any size convert without losing precision — and it all runs in your browser.