Convert Unix file permissions

How it works

1. 1

   Tick the permissions you want, or type an octal value.

2. 2

   Check the octal and symbolic results.

3. 3

   Use the value in your chmod command.

About the Chmod Permission Calculator

Unix file permissions decide who can read, write and execute a file, and chmod sets them with a three-digit octal number such as 644 or 755. Remembering which digit means what is the hard part. This calculator links a grid of checkboxes to the octal value and the rwx symbolic form, so you can go from either one to the other.

What you can do

• Tick read, write and execute for owner, group and others to build the octal number.
• Type an octal value such as 640 to see which boxes it sets.
• Read the matching symbolic form, such as rw-r-----, as shown by ls -l.
• Enter four-digit values like 0755; the leading digit is accepted.

When it works best

• Choosing safe permissions for an SSH key, a .env file or a deploy script.
• Decoding the permissions shown in a server error or an ls -l listing.
• Explaining to a teammate why 777 is a bad idea on a web server.

Things to know

• Everything is calculated in your browser.
• The first of four digits is ignored, so setuid, setgid and the sticky bit are not shown or set.
• This calculates the numeric mode only. It cannot change files; run chmod on your system with the result.
• Directories need execute permission to be opened. To convert other numbers between octal and binary, use the Number Base Converter.

Frequently asked questions