Work out octal conversion instantly with clear inputs, formula shown and shareable results.
Octal uses base 8, so each digit maps to exactly three binary digits. That is why Unix file permissions are written in octal: each digit encodes the read, write and execute bits for one class of user.
Octal to decimal
value = Σ digitₖ × 8ᵏ
493 in decimal, or rwxr-xr-x — full access for the owner and read plus execute for everyone else.
Because 8 = 2³, so each octal digit is exactly a group of three binary digits.