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Chmod Calculator

Translate between Unix file permissions, their octal notation and the symbolic string.

Chmod Calculator

Visual generator for Unix file permissions.

Scope
Read (4)
Write (2)
Execute (1)
Owner
Group
Public
Special permission bits
chmod 755 filename.txt

What Chmod Calculator does

Unix permissions are three groups of three bits: read, write and execute, for the owner, the group and everyone else. The octal shorthand encodes each group as one digit.

Set the permissions with the checkboxes to read off the octal number, or type an octal value to see which permissions it grants.

  • Toggle read, write and execute for owner, group and others
  • Enter an octal value and see the permissions it represents
  • Show the symbolic string as ls would print it
  • Include the setuid, setgid and sticky bits
  • Copy the ready-made chmod command

How to use Chmod Calculator

  1. 1

    Set the permissions

    Tick the boxes for each of owner, group and others, or type the octal value directly.

  2. 2

    Read both notations

    The octal number and the symbolic string update together, so you can see how they correspond.

  3. 3

    Copy the command

    Copy the chmod line and replace the placeholder with your filename.

Example

The most common permission sets

Input

Owner: read, write
Group: read
Others: read

Output

644  -rw-r--r--

755 (-rwxr-xr-x) is the usual equivalent for directories and executable scripts, because a directory needs the execute bit to be entered at all.

Limits and known behaviour

  • The symbolic string is shown for a regular file. A directory would begin with d, and the leading character reflects the file type rather than its permissions.
  • Access control lists, extended attributes and SELinux contexts are separate mechanisms and are not represented here.
  • The tool converts notation; it does not apply anything to any file.
  • Windows permissions work on an entirely different model and do not map onto these values.

Privacy and data handling

Runs entirely in your browser

  • Your input is processed by JavaScript running in this page. The tool sends no request anywhere, so nothing you paste is transmitted or logged by this site.
  • Nothing is saved between visits. Closing or reloading the tab discards whatever is in the fields.

Site-wide data handling, including analytics and advertising, is described in the privacy policy.

Frequently asked questions

What does 777 mean and why is it discouraged?

It grants read, write and execute to everyone on the system, including the ability to modify or replace the file. It is almost never necessary, and it is a standard way to turn a minor vulnerability into a serious one. Grant the narrowest permission that works.

Why does my directory need the execute bit?

On a directory, execute means the right to traverse into it and access files by name. Read without execute lets a user list the names but not reach the contents, which is rarely what is intended.

What is the sticky bit for?

On a shared directory such as /tmp it restricts deletion, so a user can only remove their own files rather than anyone's.