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Chmod Calculator

Set file permissions with checkboxes and convert between octal notation, symbolic notation, and a chmod command.

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Data is never sent to a server

Tool

Read (r)Write (w)Execute (x)
Owner (u)
Group (g)
Other (o)

Type an octal value (e.g. 755) or symbolic notation (e.g. rwxr-xr-x) directly to update the checkboxes.

Octal Notation
644
Symbolic Notation
-rw-r--r--
Example Command
chmod 644 filename

What is the Chmod Calculator?

This tool lets you set and inspect Linux/UNIX file permissions through intuitive checkboxes. It automatically converts between octal and symbolic notation and generates a ready-to-copy chmod command.

Key Features

  • Checkbox grid for owner/group/other × read/write/execute
  • Support for setuid, setgid, and sticky bit special permissions
  • Two-way conversion between octal (e.g. 755) and symbolic (e.g. rwxr-xr-x) notation
  • Manual entry field that parses either notation directly
  • Automatically generated, copyable example chmod command

When This Comes in Handy

  • Setting the correct permissions in server configuration or deployment scripts
  • Understanding what an existing file’s permissions (e.g. the rwxr-xr-x shown by ls -l) actually mean
  • Building complex permission sets that include special bits like setuid or setgid

How to Use

  1. Select read, write, and execute permissions for owner (u), group (g), and other (o) using the checkboxes.
  2. Optionally set special permissions such as setuid, setgid, and the sticky bit.
  3. The octal notation (e.g. 755) and symbolic notation (e.g. rwxr-xr-x) are calculated automatically.
  4. You can also type an octal or symbolic value directly into the manual entry field to update the checkboxes.
  5. Copy the generated example `chmod` command to use in your terminal.

FAQ

What is chmod octal notation?

It represents permissions as a 3-digit number (or 4 digits with special permissions) where read (r) = 4, write (w) = 2, and execute (x) = 1, summed separately for owner, group, and other. For example, "rwxr-xr-x" becomes "755".

What are setuid, setgid, and the sticky bit?

setuid (4000) makes a file run with the owner's privileges rather than the executing user's. setgid (2000) makes new files inherit the group. The sticky bit (1000), typically set on directories, prevents users other than the owner from deleting files within it.

What's the difference between 755 and 644?

755 (rwxr-xr-x) grants the owner read/write/execute and grants group/other read/execute — commonly used for executables and directories. 644 (rw-r--r--) grants the owner read/write and grants group/other read-only — commonly used for regular text files.

What does each character in symbolic notation mean?

The first character indicates the file type (- for a regular file, d for a directory, l for a symbolic link). The following 9 characters represent owner/group/other permissions in rwx order, with "-" marking an absent permission.

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