Permissions
Chmod Calculator
Calculate file permissions in octal (755) and symbolic (rwxr-xr-x) formats.
Owner
Group
Others
Octal (compact)
755
Octal (4-digit)
0755
Includes special bits as the leading digit.
Symbolic
rwxr-xr-x
About Chmod Permission Calculator
The Chmod Calculator provides a quick way to compute accurate file permissions for Linux and Unix systems. It converts between the standard octal permissions (like 755 or 644) and the symbolic rwx notation, identifying exactly who has read, write, or execute access.
Secure your servers and scripts by ensuring precise access and control lists. Understanding unix permissions prevents security vulnerabilities caused by accidental overly-permissive files (like 777). This tool helps systems administrators and developers verify the correct chmod commands for their deployment scripts.
Check or uncheck the boxes for Owner, Group, and Public permissions. The calculator will instantly show the corresponding Octal code (e.g., 755) and Symbolic text (e.g., drwxr-xr-x). You can also type an Octal number directly to see what permissions it represents.
Under the Hood
Permissions are modeled as a 12-bit integer. The lower 9 bits represent standard rwx groups (User, Group, Other), while the upper 3 bits handle special flags (SetUID, SetGID, Sticky). The tool provides a bidirectional mapping between the bitmask state, the octal representation (using standard base-8 conversion), and the symbolic string notation `drwxrwxrwx`. Computations are purely bitwise to ensure accuracy.