chmod (change mode) is a Linux/Unix command that sets file and directory permissions, controlling who can read, write, or execute a file.

755 means the owner has full permissions (read+write+execute), while group and others have read and execute only. This is the most common permission for web directories.

644 means the owner can read and write, while group and others can only read. This is the standard permission for web files like HTML, CSS, and images.

How do I use the octal input?

Type a 3-digit octal number (e.g. 755) in the input field, and the permission checkboxes will update automatically to match.

What is the difference between octal and symbolic notation?

Octal uses numbers (755), while symbolic uses letters (rwxr-xr-x). Both represent the same permissions — octal is shorter, symbolic is more readable.

Can I copy the chmod command?

Yes. Click the copy button next to the command to copy "chmod 755 filename" to your clipboard, ready to paste into your terminal.

What permissions should I use for a website?

Typically, directories use 755 and files use 644. Never use 777 on production servers as it gives everyone full access.

Does this work for directory permissions too?

Yes. chmod works the same for files and directories. For directories, execute permission means the ability to list contents.

chmod Calculator

Calculate Linux file permissions with an interactive chmod calculator — octal and symbolic.

Updated Mar 2026100% Private — runs in browser

Octal Value

Symbolic:-rwxr-xr-x

Command:chmod 755 filename

Permissions

Read (r)

Write (w)

Execute (x)

Owner (u)

Group (g)

Others (o)

Octal

Common Permissions