Chmod Calculator
Developer ToolsCalculate file permissions
| Role | Read (r) | Write (w) | Execute (x) | Octal |
|---|---|---|---|---|
| owner | 7 | |||
| group | 5 | |||
| others | 5 |
Octal
755
Symbolic
rwxr-xr-x
Command
chmod 755 filenameCommon Permission Patterns
| Octal | Symbolic | Use Case |
|---|---|---|
| 644 | rw-r--r-- | Default file — owner read/write, others read |
| 755 | rwxr-xr-x | Default directory / executable scripts |
| 600 | rw------- | Private file — SSH keys, credentials |
| 700 | rwx------ | Private directory — owner only |
| 775 | rwxrwxr-x | Shared directory — group write access |
| 666 | rw-rw-rw- | World-writable file (avoid in production) |
| 777 | rwxrwxrwx | Full permissions (security risk — use carefully) |
| 400 | r-------- | Read-only by owner — immutable config files |
| 444 | r--r--r-- | Read-only for everyone |
| 750 | rwxr-x--- | Web server directory — owner + group access |
Click any row to apply that permission.
About Chmod Calculator
Calculate Unix file permission values interactively with checkboxes and octal input.
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Frequently Asked Questions
What is chmod and how do permission numbers work?
chmod (change mode) sets file permissions in Unix and Linux systems. Each digit represents a user group: owner, group, others. Read is 4, write is 2, execute is 1. These values are added together, so 7 means full access (4+2+1) and 5 means read and execute (4+1).
What is the difference between 644 and 755?
644 (rw-r--r--) gives the owner read and write access while everyone else can only read. 755 (rwxr-xr-x) gives the owner full access and allows others to read and execute. Use 644 for regular files and 755 for directories and executable scripts.
What does the common permission patterns table show?
The reference table lists 10 frequently used permission combinations with their octal code, symbolic notation, and typical use case. Click any row to instantly apply that permission to the calculator. Patterns range from 400 (read-only by owner) to 777 (full access for everyone).
Is my data safe?
Yes! All processing happens entirely in your browser. No data is sent to any server. No data is collected, stored, or transmitted.
When should I use 600 vs 644 permissions?
Use 600 (rw-------) for sensitive files like SSH keys, API credentials, and private configuration files that only the owner should access. Use 644 (rw-r--r--) for files that others need to read but not modify, such as web content and documentation.
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