Free online chmod calculator for Unix/Linux file permissions. Convert between numeric (octal) and symbolic notation, generate chmod commands, and understand permission security levels.
Discover our collection of free online tools for developers, designers, and power users
chmod 0644 <file>chmod u=rw,g=r,o=r <file>Enter a 3 or 4 digit octal value (e.g. 755, 0644, 4755)
Can read, write
Can read
Can read
In Unix and Linux systems, every file and directory has a set of permissions that control who can read, write, or execute it. These permissions are divided into three categories: Owner (the file creator), Group (users in the same group), and Others (everyone else). The chmod command is used to change these permissions.
Our free chmod calculator makes it easy to set file permissions without memorizing octal codes. Use the visual permission matrix to toggle read, write, and execute for each role, see the numeric and symbolic results instantly, and copy the ready-to-use chmod command. Everything runs in your browser — no server required.
Toggle the checkboxes in the permission matrix to set read, write, and execute permissions for owner, group, and others. Or enter an octal value like 755 directly.
Choose from 15+ common permission presets organized by use case: files, directories, security, and special permissions. Each preset includes a description and security notes.
Check the security level indicator to understand the implications of your permission settings. The breakdown panel explains what each role can do.
Copy the generated chmod command (numeric or symbolic format) and paste it into your terminal. Both formats are shown side by side for your convenience.
| Value | Symbol | Permission |
|---|---|---|
| 0 | --- | No permission |
| 1 | --x | Execute only |
| 2 | -w- | Write only |
| 4 | r-- | Read only |
| 5 | r-x | Read + execute |
| 6 | rw- | Read + write |
| 7 | rwx | Full permission |
See both numeric (e.g. 0755) and symbolic (e.g. rwxr-xr-x) notation updated in real time.
Toggle permissions with checkboxes instead of calculating octal values manually.
Instant security level assessment with warnings for dangerous permission settings.
Common permission presets for files, directories, security, and special bits with descriptions.
Copy-ready chmod commands in both numeric and symbolic format for your terminal.
Full dark mode support for comfortable use in any lighting environment.
Chmod 755 (rwxr-xr-x) gives the owner full permissions (read, write, execute) and allows the group and others to read and execute. This is the standard permission for executable files, scripts, and directories.
644 (rw-r--r--) is for regular files that don't need to be executed — the owner can read and write, others can only read. 755 (rwxr-xr-x) adds execute permission, making it suitable for scripts, binaries, and directories.
Setuid (4xxx) makes a file execute with the owner's privileges. Setgid (2xxx) makes new files in a directory inherit the directory's group. Sticky bit (1xxx) prevents users from deleting files they don't own in shared directories like /tmp.
Chmod 777 gives every user full permissions (read, write, execute) on the file or directory. This means anyone on the system can modify or delete the file, potentially compromising security, injecting malicious code, or causing data loss. Use 755 or 750 instead.
All processing happens locally in your browser. No permission settings or data are sent to any server. Refreshing the page resets to the default (0644).