All tools
Development tools

Chmod Calculator

Calculate Unix file permissions with a click-to-toggle grid — instantly converts between numeric (755) and symbolic (rwxr-xr-x) notation.

Click-to-toggle grid Numeric ↔ symbolic Octal notation Setuid / setgid Sticky bit Copy chmod command
Get started free Sign in

Free · No credit card · 50 credits/day

Common permission presets

Octal Symbolic Typical use
755 rwxr-xr-x Directories, executable scripts, public web files
644 rw-r--r-- Regular files: HTML, CSS, config files
600 rw------- Private files: SSH private keys, .env files
700 rwx------ Private scripts, personal directories
777 rwxrwxrwx World-writable — avoid in production
444 r--r--r-- Read-only files: published content, backups
664 rw-rw-r-- Shared group editable files

Frequently asked questions

What does chmod mean?

chmod stands for "change mode" — the Unix command for setting file permission bits. Every file on a Unix/Linux system has three permission groups (owner, group, others) and three permission types (read, write, execute). chmod uses numeric octal notation (chmod 755) or symbolic notation (chmod u+rwx,g+rx,o+rx).

What is the difference between 755 and 644?

755 (rwxr-xr-x) grants the owner full permissions and everyone else read+execute. It is the standard for directories and executable scripts. 644 (rw-r--r--) grants the owner read+write and everyone else read-only — standard for regular HTML, CSS and configuration files.

What is the setuid bit?

The setuid bit (4 in the leading digit, e.g. 4755) causes an executable to run with the owner's privileges rather than the caller's. For example, /usr/bin/passwd is setuid root so regular users can change their own password. Both setuid and setgid are security-sensitive and should be used sparingly.

What is umask?

umask is the default permission mask applied when new files and directories are created. A umask of 022 means new files get 644 (666-022) and directories get 755 (777-022). Run "umask" in a shell to see your current mask. "umask 027" restricts new files to owner+group only.

Related dev tools

More tools for server and security configuration.

SSH Key Info

Analyze your SSH public key — type, bit length, fingerprints and security rating.

 Bcrypt Generator

Hash and verify passwords with bcrypt — choose the cost factor.

 .htpasswd Generator

Generate bcrypt Apache password entries for .htpasswd files.

Get the right permissions first time

Free account. 50 credits per day. Access to 75+ tools instantly.

Create free account →