Chmod calculator

How it works

Each checkbox maps to a bit: read=4, write=2, execute=1; the checked values for a role are summed to make one octal digit (0–7), and the three digits together (owner, group, other) form the chmod value. Typing an octal number directly does the reverse, decoding each digit's bits back into checkboxes with a bitwise AND against 4, 2, and 1.

FAQ

Why can permissions only be 0-7 per digit?

Because each digit is three bits (read, write, execute) added together — the maximum is 4+2+1=7 (all three enabled) and the minimum is 0 (none), so no combination of rwx can produce a digit outside that range.

What does chmod 755 actually mean?

Owner (7 = rwx) gets full access, while group and other (5 = r-x) can read and execute but not write — a common setting for scripts and directories that others should be able to run or list but not modify.