Chmod Calculator
Click checkboxes to build Unix file permissions or type an octal value directly. Runs entirely in your browser.
| Role | Read (4) | Write (2) | Execute (1) |
|---|---|---|---|
| Owner User | |||
| Group Project Team | |||
| Others Public |
About Unix File Permissions
Learn how POSIX permission bits, octal arithmetic, and special flags secure Unix and Linux systems.
File access rights on Unix-like operating systems are divided into three core user classes: Owner (user), Group, and Others (public). Each class can be granted individual permissions for Read (4), Write (2), and Execute (1). Summing these values gives you the familiar three-digit octal notation used in administration commands like chmod.
Octal Math Simplified
Read (4) + Write (2) + Execute (1) added per category yields values like 755 or 644.
SSH & Config Locking
Secure private keys and configuration files using strict modes like 600 or 400.
Web Directories & Files
Apply standard web defaults: 755 for directory traversal and 644 for static files.
100% Secure & Private
Everything executes client-side. Your file paths and settings never leave your browser.
One-Click Copy
Copy ready-to-run terminal commands directly into your clipboard.
Special Bits Supported
Easily configure SetUID, SetGID, and Sticky bit options with 4-digit octal output.