Umask Calculator

About this calculator

On Linux and Unix systems, new files and directories start from maximum default permissions — 666 (rw-rw-rw-) for files and 777 (rwxrwxrwx) for directories — and the umask value subtracts specific permission bits from that maximum using a bitwise AND with the complement of the mask. A umask of 022, for example, strips group and other write permission, leaving new files at 644 and new directories at 755.

System administrators and developers set the umask in shell profiles or service configs to control the default access level of everything a process creates, which matters for security on shared servers and multi-user systems. This calculator takes a umask value and shows the resulting default permissions for both new files and new directories.