Linux Chmod Permission Calculator

Modes you will use most

644 suits ordinary files: the owner edits, everyone else reads. 755 suits directories and scripts that others must run. 600 is for secrets such as ~/.ssh/id_ed25519 or a .env file, and 700 for the ~/.ssh directory itself; SSH refuses a private key that others can read. 777 is almost never the answer: when a web server cannot write a file, change the owner with chown rather than opening the file to everyone.

Directories read the bits differently

On a directory, r lets someone list the names inside, w lets them create and delete entries, and x lets them enter it and reach files by path. That is why chmod -R 644 on a folder locks everyone out of its subdirectories. Use chmod -R u=rwX,go=rX instead: the capital X adds execute only to directories and to files that already had it.

A four-digit mode such as 1777 or 4755 carries a leading digit for the sticky, setgid, and setuid bits. This calculator covers the three standard digits, which is what everyday files need.

How to use it

1. Toggle Read, Write, and Execute checkboxes for Owner, Group, and Others.
2. View the instant octal code (e.g. 755) and symbolic notation.
3. Copy chmod commands for files or recursive directories.

Privacy & limitations

Calculations execute entirely in client-side JavaScript.