Chmod Calculator

What this tool does

Unix file permissions are three bits — read, write, execute — repeated for the file owner, its group and everyone else, plus optional setuid, setgid and sticky bits. This calculator keeps the checkboxes, the three- or four-digit octal number and the rwxr-xr-x symbolic form in sync, so you can start from whichever representation you already have and read off the other two.

How to use it

1. Tick the read, write and execute boxes for owner, group and other.
2. Optionally set setuid, setgid or sticky under special permissions.
3. Or type an octal value directly — the checkboxes update to match.

Privacy

This tool runs entirely in your browser. Your input is never uploaded, stored or shared — closing the tab removes it.

Frequently asked questions

What does the octal number mean?

Each digit is the sum of read (4), write (2) and execute (1) for one class of user, in the order owner, group, other. 755 means the owner has all three, group and other have read and execute only.

What are setuid, setgid and sticky for?

Setuid and setgid run a program as its owner or group instead of the user who launched it; sticky, set on a directory, stops users from deleting files they do not own. They appear as a fourth leading octal digit.

Why does the symbolic form show s or t instead of x?

A lowercase s or t means the execute bit and the matching special bit are both set; an uppercase S or T means the special bit is set but execute is not.