Chmod Calculator
Calculate Linux file permissions with an interactive chmod calculator. Convert between numeric (755) and symbolic (rwxr-xr-x) notation. Free online tool.
How to Use
- Toggle the Read, Write, and Execute checkboxes for Owner, Group, and Others.
- The numeric value, symbolic notation, and chmod command update instantly.
- Alternatively, type a numeric value (e.g.,
644) into the input field and the checkboxes will update to match. - Click Copy next to any output to copy it to your clipboard.
Common Permissions
| Numeric | Symbolic | Use Case |
|---|---|---|
755 | rwxr-xr-x | Directories, executable scripts, web server root |
644 | rw-r—r— | Regular files, HTML/CSS, config files |
600 | rw------- | Private files (SSH keys, .env) |
700 | rwx------ | Private directories, ~/.ssh |
777 | rwxrwxrwx | World-writable (avoid in production) |
444 | r—r—r— | Read-only for everyone |
750 | rwxr-x--- | Owner full, group read/execute, others none |
664 | rw-rw-r— | Shared files where group members can edit |
Worked Examples
Setting up a web server file
Your web server serves static HTML. The web server process (running as www-data) only needs to read the files, while you as the owner need to edit them:
chmod 644 index.html # Owner: read+write, Group/Others: readThis gives you rw-r—r— — you can edit, the server can read, and no one can execute the file.
Making a script executable
You’ve written a deployment script and need to run it. Others on the team should be able to run it too but not modify it:
chmod 755 deploy.sh # Owner: full, Group/Others: read+executeThis gives you rwxr-xr-x. Now you can run ./deploy.sh directly.
Protecting SSH keys
SSH refuses to use a private key if its permissions are too open. Lock it down to owner-only:
chmod 600 ~/.ssh/id_rsa # Owner: read+write, no one elseResult: rw-------. SSH requires 600 or stricter for private key files.
FAQ
What is chmod?
chmod (change mode) is a Unix/Linux command that sets file and directory permissions. It controls who can read, write, or execute a file. Permissions are assigned to three classes: the file owner, the group, and all other users.
What do the chmod numbers mean?
Each digit represents a permission class (owner, group, others). The digit is the sum of: 4 (read), 2 (write), and 1 (execute). For example, 7 = 4+2+1 (read+write+execute), 5 = 4+1 (read+execute), 0 = no permissions.
What are common chmod values like 755 and 644?
755 (rwxr-xr-x) is standard for directories and executable scripts — owner has full access, others can read and execute. 644 (rw-r--r--) is standard for regular files — owner can read/write, others can only read. 600 (rw-------) is used for private files like SSH keys.
Is my data sent anywhere?
No. This calculator runs entirely in your browser using JavaScript. No data is transmitted to any server.