chmod (change mode) is a Unix/Linux command that sets file and directory permissions. It controls who can read, write, and execute files. Permissions are set for three groups: Owner (file creator), Group (users in the same group), and Others (everyone else).

r = Read (view file contents or list directory), w = Write (modify file or create/delete files in directory), x = Execute (run file as program or enter directory). A dash (-) means the permission is not granted.

Is my data stored on the server?

No. All calculations happen directly in your browser using JavaScript. Nothing is sent to any server.

How do I use chmod on the command line?

Use: chmod 755 filename — to set numeric permissions. Or chmod u+x filename — to add execute for owner. The calculator generates the full command for you to copy and paste.

Yes, completely free with no registration required. Use it as many times as you need.

Chmod Calculator

Calculate Unix file permissions visually. Convert between numeric (755) and symbolic (rwxr-xr-x) notation. Everything runs in your browser.

Toggle checkboxes to set permissions, or enter a numeric value below. The chmod command is generated automatically.

Numeric

755

Symbolic

rwxr-xr-x

Enter numeric:

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$ chmod 755 filename

755 (rwxr-xr-x): Owner can read, write, and execute. Group and Others can read and execute. Common for directories and executable scripts.

How It Works

This chmod calculator runs entirely in your browser — no data is sent to any server. Toggle permission checkboxes or enter a numeric value to see the conversion instantly.

Permission Structure

Unix file permissions are divided into three groups: Owner (the file creator), Group (users in the same group), and Others (everyone else). Each group has three permissions: Read (r=4), Write (w=2), and Execute (x=1).

Numeric Notation

Each digit is the sum of permission values: Read (4) + Write (2) + Execute (1). For example, 7 = 4+2+1 = rwx, 5 = 4+0+1 = r-x, 6 = 4+2+0 = rw-, 0 = --- (no permissions). The three digits represent Owner, Group, Others.

Symbolic Notation

A 9-character string like rwxr-xr-x — three groups of three characters. Each character is either the permission letter (r, w, x) or a dash (-) meaning not granted. First group = Owner, second = Group, third = Others.

Privacy First

All calculations run locally in your browser using JavaScript. No data is sent to any server.

Frequently Asked Questions (FAQ)

Q: What is chmod?

A: chmod (change mode) is a Unix/Linux command that sets file and directory permissions. It controls who can read, write, and execute files.

Q: What do the numbers in chmod 755 mean?

A: Each digit represents Owner, Group, Others. The digit is Read (4) + Write (2) + Execute (1). So 7 = rwx, 5 = r-x, 0 = no access.

Q: What is the difference between 644 and 755?

A: 644 (rw-r--r--) is for regular files. 755 (rwxr-xr-x) is for directories and executables — adds execute permission.

Q: What does rwx mean?

A: r = Read (view), w = Write (modify), x = Execute (run as program or enter directory). A dash (-) means not granted.

Q: What are common chmod values?

A: 644 — standard files. 755 — directories/scripts. 600 — SSH keys. 777 — full access (not recommended). 400 — read-only owner.

Q: Is chmod 777 safe?

A: No. 777 gives everyone full access including write. This is a security risk. Use 755 for directories and 644 for files instead.

Q: How do I use chmod?

A: Run chmod 755 filename in terminal. Add -R for recursive: chmod -R 755 directory/.

Q: Is this tool free?

A: Yes, completely free with no registration required.