Chmod Calculator
Calculate Linux file permissions in numeric and symbolic notation.
Processed locally in your browserBuild the correct Linux file permission value visually with this free online chmod calculator.
| read | write | execute | |
|---|---|---|---|
| Owner | |||
| Group | |||
| Other |
Special:
Numeric
0755
Symbolic
rwxr-xr-x
Options:
Command
chmod 0755 /path/to/fileCommon Presets
Popular Permissions Reference
| Octal | Symbolic | Use Case |
|---|---|---|
| 755 | rwxr-xr-x | Web directories, scripts |
| 644 | rw-r--r-- | HTML, CSS, images, config files |
| 777 | rwxrwxrwx | Temp dirs (insecure, avoid in prod) |
| 600 | rw------- | SSH keys, .env, private configs |
| 700 | rwx------ | Private scripts, home dirs |
| 664 | rw-rw-r-- | Shared group files |
| 750 | rwxr-x--- | Group-accessible directories |
| 400 | r-------- | Read-only secrets, certificates |
| 444 | r--r--r-- | Read-only for everyone |
| 555 | r-xr-xr-x | Read+execute only, no write |
| 1777 | rwxrwxrwt | /tmp directory (sticky bit) |
| 2755 | rwxr-sr-x | Setgid directories |
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How to Use
Build the correct Linux file permission value visually with this free online chmod calculator.
- Set permissions with the matrix. Click the checkboxes for Read, Write, and Execute across Owner, Group, and Others columns. The numeric and symbolic values update in real time.
- Or enter a numeric value. Type a three-digit octal number like 755 or 644 into the numeric input and the permission matrix updates to show exactly what each digit means.
- Use a preset. Click common presets like 755 (standard directory), 644 (regular file), or 600 (private file) to set the matrix instantly.
- Set special bits if needed. Toggle setuid, setgid, or sticky bit for advanced permission scenarios like shared directories or privileged executables.
- Copy the command. Use the copy button to grab the complete chmod command (e.g., chmod 755 filename) ready to paste into your terminal.
This chmod calculator helps you avoid permission errors that can cause "Permission denied" issues or security vulnerabilities from overly permissive settings. Everything runs in your browser — no data is sent to any server.
Features
- ✓Interactive permission matrix
- ✓Numeric and symbolic notation
- ✓Special bits (setuid, setgid, sticky)
- ✓Common permission presets
- ✓Copy chmod command
- ✓Real-time conversion
Frequently Asked Questions
- What is chmod?
- chmod (change mode) is a Unix/Linux command that sets the read, write, and execute permissions on files and directories for three groups: the owner, the group, and all other users. Use this chmod calculator to build the correct permission value without memorizing the numeric codes.
- How do Linux file permissions work?
- Linux file permissions are divided into three permission sets — owner, group, and others — each with three bits: read (r=4), write (w=2), and execute (x=1). The chmod calculator adds the bit values together for each set to produce a three-digit octal number like 755 or 644.
- What does chmod 755 mean?
- chmod 755 gives the owner full read, write, and execute permissions (7 = 4+2+1) and grants the group and others read and execute permissions only (5 = 4+1). It is the standard permission for web server directories and executable scripts that everyone needs to run but only the owner should modify.
- What is the difference between numeric and symbolic chmod notation?
- Numeric (octal) notation expresses permissions as a three-digit number such as 644, while symbolic notation uses letters and operators like u=rw,go=r. Both achieve the same result; the chmod calculator converts between both formats instantly so you can use whichever form your workflow requires.
- What are the most common chmod permission values?
- The most commonly used values are 755 (directories and executables), 644 (regular files), 600 (private files like SSH keys), and 777 (full access for everyone, generally discouraged for security reasons). This chmod calculator includes presets for all of these so you can apply them with a single click.