Set File Permissions
Common Use Cases
Click any use case to apply its permissions:
Understanding Permissions
Each permission type has different meaning for files vs directories:
Quick Reference
| Numeric | Symbolic | Description |
|---|---|---|
| 644 | rw-r--r-- | Standard file (owner write, all read) |
| 755 | rwxr-xr-x | Executable/directory (owner full, others read+execute) |
| 700 | rwx------ | Owner only (complete privacy) |
| 600 | rw------- | Owner read/write only (secrets, keys) |
| 444 | r--r--r-- | Read-only for everyone |
| 777 | rwxrwxrwx | ⚠️ Full access for everyone (avoid!) |
| 775 | rwxrwxr-x | Group collaboration (owner+group full) |
| 664 | rw-rw-r-- | Group editable file |
About Chmod
chmod (change mode) is a Unix/Linux command that sets file and directory permissions.
Permissions control who can read, write, or execute files on a system.
The Three Permission Groups
- Owner (u) — The user who owns the file
- Group (g) — Users in the file's group
- Others (o) — Everyone else on the system
Numeric vs Symbolic Notation
Numeric (octal): Three digits, each 0-7. Calculate each digit by adding: read (4) + write (2) + execute (1).
Example: 755 = 7 (rwx) for owner, 5 (r-x) for group, 5 (r-x) for others.
Symbolic: 10 characters showing file type and all permissions.
The first character is file type (- for file, d for directory),
followed by 3 sets of rwx for owner, group, and others.
Security Best Practices
- 🔒 Never use
777in production — it's a security risk - 🔑 Keep SSH keys at
600(SSH will reject insecure key files) - 📁 Web directories typically need
755for proper access - 📄 Config files with passwords should be
600or640 - 🏠 Home directories should be
700or750
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Chmod Calculator FAQ
What is Chmod Calculator?
Chmod Calculator is a free developer tools tool that helps you Convert between chmod numeric and symbolic notation.
How do I use Chmod Calculator?
Enter your input values, review the calculated output, and adjust inputs until you reach the result you need. The result updates in your browser.
Is Chmod Calculator private?
Yes. Calculations run locally in your browser. Inputs are not uploaded to a server by default, and refreshing the page clears session data.
Does Chmod Calculator require an account or installation?
No. You can use this tool directly in your browser without sign-up or software installation.
How accurate are results from Chmod Calculator?
This tool applies standard formulas or deterministic processing logic for estimates. For medical, legal, tax, or investment decisions, verify with a qualified professional.
Can I save or share outputs from Chmod Calculator?
You can bookmark this page and copy outputs manually. Results are not persisted in your account and are typically not embedded in the URL.