🔐 Chmod Calculator
Choose read, write, and execute permissions for owner, group, and other to get the matching chmod octal number and symbolic notation.
What this calculator does
On Linux and Unix systems, file permissions control who can read, write, or execute a file, split into three groups: the file’s owner, its group, and everyone else. This calculator builds the numeric (‘chmod’) permission code from simple yes/no choices.
How the calculation works
Each permission is worth a fixed value: read = 4, write = 2, execute = 1. Adding the values you enable for a group gives that group’s single digit (0-7), and the three digits together (owner, group, other) form the familiar three-digit chmod number, such as 755. The tool also shows the equivalent symbolic notation, like rwxr-xr-x.
This mirrors exactly how the Unix ‘chmod’ command interprets numeric permission modes — it’s a reference and planning tool, not a substitute for understanding your system’s actual security requirements.