Chmod Permission Calculator

Calculate and convert Linux / Unix file permissions between octal (755) and symbolic (rwxr-xr-x).

About this tool

Demystify Unix permissions with instant bidirectional conversion between numeric octals and symbolic representations.

How to use this tool

  1. Enter an octal number like 755 or 644, or symbolic string like rwxr-xr-x.
  2. Click Run Chmod Calculator.
  3. View the full permission matrix and copy the shell command.

How it works

Computes bitwise masks for User, Group, and Others (Read=4, Write=2, Execute=1), producing commands and descriptions.

When to use this tool

  • Configuring web server permissions for Nginx, Apache, or SSH keys (600, 700).
  • Teaching and understanding Linux security fundamentals.

Frequently asked questions

What is the recommended permission for SSH keys?

SSH private keys typically require chmod 600 (read/write for owner only).

Limitations

Covers standard 3-digit and 4-digit Unix file permissions.

Privacy

Runs entirely in local browser memory.