Unix umask Calculator
Calculate conventional new-file and directory modes from a numeric Unix umask, or derive a compatible umask locally.
Accepts three octal digits, or four with one leading zero. Symbolic umasks and full commands are not supported. Input stays in this browser.
This is a local calculation of conventional creation modes; it does not read or change host settings. It does not prove effective access, the actual umask, ACLs, ownership, mount options, or system policy.
Derive numeric umask
Both fields need three octal digits, with one optional leading zero. The conventional regular-file request has no execute bits.
027Produces file 0640 / 0750
umask 027Conventional creation-mode preview
This preview uses conventional requested modes of 0666 for files and 0777 for directories; an application can request fewer permissions.
0644Symbolic permissions: rw-r--r--0755Symbolic permissions: rwxr-xr-x- File request
0666 & ~022 = 0644- Directory request
0777 & ~022 = 0755
How to use this tool
Enter a numeric umask to compare the conventional 0666 and 0777 requested modes, or enter both desired modes to derive only an exact compatible result.
When not to use it
Do not treat this conventional calculation as proof of effective access or actual host policy; ACLs, application requests, and system controls can change the created mode.
Read the guide →