umask Calculator

See exactly what permissions a Unix umask produces on newly created files and directories. Files are created with a base of 666 (rw-rw-rw-) and directories with 777 (rwxrwxrwx); the umask is then AND-complemented away (base & ~umask), so 022 yields 644 files and 755 directories. Also works in reverse: enter the file or directory permissions you want and get the umask that produces them. Pure bit arithmetic, in your browser.