Chmod Calculator

Tick the permissions you want, or type a number like 755. The octal value, the symbolic form and the command update together.

  • Free
  • No Sign-Up
  • Runs in Your Browser

Owner

Group

Others

Tick permissions above, or type a value such as 644.

How to Use

How to use the Chmod Calculator

  1. 01

    Set permissions

    Tick read, write and execute for the owner, the group and everyone else.

  2. 02

    Or type a value

    Enter 644, 0755 or rwxr-x--- and the boxes follow.

  3. 03

    Copy the command

    chmod with your file name, ready to paste.

VPS & Linux

About the Chmod Calculator

How the numbers work

Each digit is one class of user (owner, group, others) and is the sum of read (4), write (2) and execute (1). 7 is all three; 5 is read and execute; 4 is read only. So 755 means the owner can do everything and everyone else can read and execute.

A fourth leading digit sets special bits: setuid (4), setgid (2) and sticky (1). 1777 is the usual mode for /tmp, where anyone can create files but only delete their own.

ModeTypical use
644Ordinary files: web pages, config
600Private files: SSH keys, .env, credentials
755Directories and scripts
700Private directories, such as ~/.ssh
640Config readable by a service's group
775Shared project directories
1777/tmp and shared upload areas

Never use 777

777 lets any user or process on the server change the file. On a web server it is how a compromised plug-in becomes a compromised site. If something only works with 777, fix the owner (chown) instead.

Common chmod Values

400440444500550555600640644660664666700711750755770775777177727754755

What it can't tell you

  • Access control lists (setfacl) and SELinux labels can allow or deny access regardless of these bits.

Frequently asked questions

What does chmod 755 mean?
Owner: read, write and execute. Group and others: read and execute. It is the normal mode for directories and scripts.
What permissions should an SSH private key have?
600 (read and write for the owner only). SSH refuses keys that others can read. The ~/.ssh directory should be 700.
What is the difference between 644 and 664?
664 also lets the file's group write to it. Use it for files a team edits together; 644 otherwise.

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