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Chmod Calculator

Interactive Unix file permissions calculator — toggle checkboxes or enter numeric values to see chmod commands instantly.

Common Presets

Numeric Value

Numeric

755

Symbolic

-rwxr-xr-x

Command

chmod 755

What this means

Owner: can read, write, execute
Group: can read, execute
Others: can read, execute

About Chmod Calculator

Free online chmod calculator for Linux and Unix file permissions. Use the interactive permission matrix to toggle read, write, and execute permissions for owner, group, and others — or enter a numeric value like 755 to see the corresponding checkboxes and symbolic notation. Includes common presets (644, 755, 777, 600, etc.) with descriptions, a plain-English explanation of what each permission allows, and one-click copy of the chmod command. Essential for developers, sysadmins, and anyone working with Linux servers. 100% browser-based, no signup required.

Frequently Asked Questions

What is chmod?▾

chmod (change mode) is a Unix/Linux command that sets file and directory permissions. It controls who can read, write, and execute a file. Permissions are assigned to three roles: the file owner, the group, and all other users.

What does chmod 755 mean?▾

chmod 755 means the owner can read, write, and execute (7 = 4+2+1), while the group and others can only read and execute (5 = 4+1). This is the standard permission for directories and executable scripts on Linux.

What does chmod 644 mean?▾

chmod 644 means the owner can read and write (6 = 4+2), while the group and others can only read (4). This is the default permission for regular files — the owner can edit the file, and everyone else can only view it.

How do permission numbers work?▾

Each digit (0-7) represents the sum of: Read (4) + Write (2) + Execute (1). So 7 = read+write+execute, 6 = read+write, 5 = read+execute, 4 = read only, 0 = no permissions. Three digits represent owner, group, and others respectively.

What is the difference between owner, group, and others?▾

Owner is the user who created the file. Group is a set of users assigned to the file's group (set with chgrp). Others is everyone else on the system. Each role can have different permission levels.

Is this tool free?▾

Yes, completely free with no signup required. All calculations happen in your browser — nothing is sent to any server.

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