The Unix Chmod Calculator helps you determine the correct file permission values for Linux, macOS, and other Unix-based systems. Use the interactive checkbox interface to set read, write, and execute permissions for owner, group, and others — then instantly see both numeric (octal) and symbolic notation.
Step-by-Step
Set permissions visually — Use the 3×3 grid of checkboxes to toggle read (r), write (w), and execute (x) for Owner, Group, and Others.
Or enter a numeric value — Type an octal value like 755 or 644 into the numeric input to see the corresponding checkboxes update.
Or enter symbolic notation — Type symbolic notation like rwxr-xr-x to set permissions from the symbolic string.
Review all notations — See the permission displayed in octal (755), symbolic (rwxr-xr-x), and as a full chmod command.
Copy the command — Click to copy the complete chmod 755 filename command ready to paste into your terminal.
Features
Interactive Checkboxes — A visual 3×3 grid showing Owner, Group, and Others rows with Read, Write, and Execute columns. Toggle any combination instantly.
Bidirectional Input — Enter permissions via checkboxes, octal numbers, or symbolic strings. All three representations update in real time.
Common Presets — Quick buttons for frequently used permission sets: 755 (standard directory), 644 (standard file), 700 (private), 777 (full access), and more.
Permission Explanation — Each permission level includes a plain-English description of what it means (e.g., "Owner can read, write, and execute; Group can read and execute").
Command Output — Generates the full chmod command string, including recursive (-R) option for directories.
Special Bits — Supports setuid, setgid, and sticky bit for advanced permission scenarios.
Common Use Cases
Server Configuration — Set correct permissions for web server files (644) and directories (755) to prevent security issues.
Script Deployment — Make shell scripts executable with chmod 755 or restrict access with chmod 700.
SSH Key Security — Ensure SSH keys have the correct 600 permissions required by the SSH client.
Shared Hosting — Calculate permissions for PHP files, upload directories, and configuration files on shared hosting environments.
Docker & CI/CD — Set file permissions in Dockerfiles and deployment scripts where incorrect permissions cause build failures.
Why Use This Tool
Unix file permissions are one of those things that every developer needs to get right but few have memorized beyond 755 and 644. This calculator removes the guesswork with an interactive visual interface that translates between all three notation systems. It's especially valuable for developers who work primarily on Windows or macOS but deploy to Linux servers. No commands to remember — just click and copy.