Chmod Calculator

Compute your chmod permissions and commands with this online calculator.

Owner (u)Group (g)Public (o)
Read (4)
Write (2)
Execute (1)
Numeric
004
Octal mode
Symbolic
-------r--
File notation

Frequently Asked Questions

What is chmod?

chmod is a Unix command used to change the access permissions of files and directories. The name is an abbreviation of "change mode". The command modifies the file system modes of files and directories.

What do the numbers mean in chmod?

In the numeric notation of chmod, each digit represents specific permissions:

  • 4 stands for "read permission"
  • 2 stands for "write permission"
  • 1 stands for "execute permission"
  • 0 stands for "no permission"

These values are added together to create the final permission value for each user group. For example, a permission of 7 (4+2+1) means read, write, and execute permissions.

What does the symbolic notation mean?

The symbolic notation consists of 10 characters:

  • The first character indicates the file type (- for regular file, d for directory)
  • Characters 2-4 represent the owner permissions (r=read, w=write, x=execute, -=no permission)
  • Characters 5-7 represent the group permissions
  • Characters 8-10 represent the permissions for others (public)